In this paper, the prediction of flexural strength was investigated using machine learning methods for concrete containing supplementary cementitious materials such as silica fume. First, based on a database of suitable characteristic parameters, the flexural strength prediction was carried out using linear (LR) model, random forest (RF) model, and extreme gradient boosting (XGB) model. Subsequently, the influence of each input parameter on the flexural strength was analyzed using the SHAP model based on the optimal prediction model. The results showed that LR, RF, and XGB enhanced the accuracy of forecasting sequentially. Among the characteristic parameters, the most significant effect on the flexural strength of concrete is the water-binder ratio, and the water-binder ratio shows a negative correlation with flexural strength. The effect of maintenance age on flexural strength is second only to the water-binder ratio, and it shows a positive trend. When the amount of fly ash is less than 40% and the amount of slag or silica fume is less than 30%, the correlation between the amount of supplementary cementitious materials and flexural strength fluctuates and a positive peak in flexural strength is observed. However, at a dosage greater than the above, the supplementary cementitious materials all reduce flexural strength. The interaction interval and the degree of interaction between the supplementary cementitious materials and the cement content also differ in predicting flexural strength. Among the many mechanical properties, strength is one of the most basic indicators. The study of concrete strength can be traced back to the beginning of the invention of concrete materials. Usually, the strength of concrete includes compressive strength and flexural strength, etc.4. For some structural members with special force and support requirements, the flexural strength of concrete must meet the requirements, the in-depth study of which is extremely important6.The mechanical properties of concrete have been of great interest8. These studies have greatly enriched the understanding of the factors influencing the flexural strength. Among the many factors affecting the flexural strength of concrete, the composition of raw materials is one of the most basic and important factors10. Among the raw materials, the connection between cement and strength is more complex and important compared to other raw materials such as aggregates because the hydration products of cement are directly related to strength12. However, the massive use of cement will produce more greenhouse gases such as carbon dioxide, which aggravates environmental pollution and contradicts the current promotion of energy saving and carbon neutrality13. This has led to a gradual shift of attention to the development of cementitious materials with a certain cementing capacity and low carbon emissions. Compared to cement, supplementary cementitious materials such as fly ash, slag, silica fume, and metakaolin are more environmentally friendly both in preparation and use17. This makes it important to study in depth the effect of supplementary cementitious materials on the mechanical properties  of concrete. Currently, there have been many studies on the strength of concrete containing supplementary cementitious materials, as summarized in Table During the study of concrete flexural strength, specimens were usually tested on the basis of changing the raw material ratio, curing conditions, and the curing age34. For example, Nguyen et al.35 studied the compressive strength of concrete by machine learning model. Zeng et al.36 used deep learning theory to predict achieved accurate prediction of compressive strength of concrete. However, most of the aforementioned studies have focused on concrete compressive strength. Few studies have been conducted on the flexural strength of concrete using machine learning, and no studies have been reported on the flexural strength of concrete containing supplementary cementitious materials. Therefore, there is a need to conduct scientific machine learning modeling studies for the flexural strength of concrete containing supplementary cementitious materials to promote the development of flexural strength of low-carbon concrete.The above studies have provided a significant boost to the related field and have led to a better understanding of it. However, most of these studies have been carried out by traditional experimental means, i.e., by controlling specific ages, specific water-binder ratios, etc., and obtaining specific values using a press machine. This will make the concrete containing supplementary cementitious materials in some projects with large volume and very high strength characteristics requirements, which will increase the experimental labor and material as well as time costs. Moreover, due to the influence of multiple factors, the final test results may be different from the actual engineering application. Therefore, the search for a concrete strength research method that can integrate multiple strength influencing factors with high efficiency and accuracy is on the agenda. With the development of computer science, some researchers have introduced machine learning into the study of concrete strength40. The existing studies were synthesized and a database covering the appropriate feature parameters was established. Based on this database, modeling studies were conducted using the linear (LR) model, random forest (RF) model, and extreme gradient boosting (XGB) model. The purpose of the above machine learning model selection is first to verify whether there is a linear relationship between various feature parameters, and then select two integrated machine learning models that are currently widely used for in-depth analysis. On the basis of the optimization model, the characteristic features were investigated based on the Shapley additive interpretation (SHAP).In view of the above, this study selected fly ash, slag, and silica fume, which are three widely used supplementary cementing materials at presentThere are numerous elements affecting the flexural strength of concrete (F_S), including water-binder ratio, aggregate content, etc. For concrete containing supplementary cementitious materials such as fly ash, slag, and silica fume, the admixture of supplementary cementitious materials is also an important influencing factor. Therefore, this study summarizes the factors influencing the strength of concrete with supplementary cementitious materials according to the possible differences in the process of making and maintaining concrete. First, in the preparation stage of concrete with supplementary cementitious materials, cement as the main cementitious material, the influence of cement content (cem_con) on the flexural strength of concrete cannot be ignored. Taking the cement admixture as a benchmark, the admixture of fly ash (FA_con), slag (S_con), and silica fume (SF_con) as alternative cement materials in the concrete is also the focus of this study. As an important participant in the hydration process of cementitious materials that cannot be ignored, the water content has an important effect on the strength. Therefore, the water-binder ratio (w_b) is also a characteristic focused on the study. Aggregate, as the component with the largest proportion of the three-phase composition of concrete, also has an important influence on the flexural strength of concrete, so fine aggregate content (Fine_A_con) and coarse aggregate content (Coarse_A_con) are set as characteristic parameters as well. During the curing of concrete, the hydration process of the cementitious material changes with the increase of curing time, so the curing age (Age) also has an important influence on the flexural strength. It is worth noting that the curing temperature and the curing humidity also affect the hydration of the cementitious materials during the curing of concrete specimens, which in turn affects the flexural strength of concrete, but these two are not considered characteristic parameters in this study. The curing temperatures of the selected concrete specimens were in the range of 20 ± 2 °C and the relative humidity fluctuated in the range of 60 ± 5%.60, and 373 valid data sets were compiled. The data on flexural strength of 373 groups of concrete were counted, and the mathematical characteristics of the input and output parameters were obtained as shown in Table When using machine learning methods for predictive modeling of material properties, a database covering all feature parameters with a sufficient amount of data is required. A good database contributes to the successful implementation of machine learning modeling and helps to improve the accuracy of subsequent feature parameter analysis. In this study, eight sets of input parameters  and one set of output parameters (F_S) were set according to the influencing factors given in "i is data sample; m is the number of i; yi, The requirements for the database are to ensure that, in addition to the quantity and quality of the dataset, there are no significant linear relationships between the feature parameters. When the linear relationship between the feature parameters is strong, it will affect the model prediction accuracy. In order to characterize the linear relationship between different feature parameters, statistical analysis is performed using Pearson correlation coefficient (PCC) in Eq. . The i iThe data hot map of PCC values for all input parameters and output parameters is shown in Fig. Many machine learning models have been successfully validated in the study of performance prediction of concrete materials. The most basic model is the LR model, which has a simple modeling process, simple analytical ideas, and fast computation speed, and was widely used before the integrated machine learning system was proposed. The calculation principle of the LR model is shown in Fig. 17.Integrated algorithmic models, as emerging machine learning models, possess more sophisticated computational procedures that can significantly improve prediction accuracy compared to linear model systems. Machine learning is accomplished by constructing multiple learners that adopt specific strategies. The purpose of the integrated algorithm is to construct a strong learning machine from multiple weak learners. This leads to a better analysis of various parameter features61. When using the bagging method for calculations. During processing, strength learners are obtained by processing many weaker learners. Subsequently, the average value is processed.The base learner chosen for modeling the flexural strength of concrete through the RF model is the decision tree. Autonomous aggregation algorithm (bootstrap aggregation) for learners61.This model is an extended extension of the bag method in which the schematic diagram is presented in Fig. 35. Figure Among centralized machine learning systems, the XGB model is a rapidly developing and widely used efficient learning model because it's fast, flexible and lightweight. The XGB model was also utilized as a decision tree to serve as the basic collector for machine learning. The integrated learning method used in the XGB model is the BoostingV number of tree structures , as shown in Eq. , it is Li and Pi in the above equation are shown in Eq.  is the prediction result i; u0 is the model baseline; xij denotes the j parameter for sample i; g(xij) is the devote in f(xi). f(xi) has the uniqueness17. In PYTHON, the calculation is analyzed by SHAP. Based on the data in the database, the feature values are obtained using the XGB model.The analytical model used in analyzing the effect of various parameters on flexural strength is SHAPn in Eq. :13\documThe SHAP value can characterize both the parameter with the highest degree of influence when analyzing the influence of a parameter and the influence process within the parameter range. In this case, the impact is positively correlated for SHAPM values greater than 0 and negatively correlated for values less than 0.Based on the previous comparison of the computational results of the three machine learning models, it was demonstrated that the XGB model performed optimally in predicting the flexural strength of concrete. Therefore, in this study, the SHAP model was used to analyze the effect of various characteristic factors on the flexural strength of concrete based on the XGB model.The gradient of the strength influenced by the eight input parameters affecting the flexural strength of concrete was first determined and characterized using SHAP mean values, and the results are shown in Fig. To further analyze the effects of various input parameters on the flexural strength of concrete and to provide insight into the trend of their effects on flexural strength from the numerical changes of the input parameters, the SHAP values of the input parameters shown in Fig. Combining Figs. 3, the variation of SHAP values showed fluctuation with extreme values around 370 kg/m3. This indicates that the strength will have a peak value at a cement admixture of 370 kg/m3. However, since in this study, there is cement along with supplementary cementitious materials, the effect of cement needs to be analyzed together with the three supplementary cementitious materials. The SHAP values of the two aggregates show similar trends with the aggregate content. Analyzing Fig. The relation of the effect of various parameters on the strength is illustrated in Fig. Then the effect of the three supplementary cementitious materials on the flexural strength of concrete is analyzed, and it can be found from the figure that FA_con and SF_con show a similar trend to w_b affecting the flexural strength of concrete on some intervals. This indicates that in terms of strength, the above two characteristic parameters have less flexural strength when they are present in concrete in larger amounts. However, in marked contrast to w_b, the fluctuation of the SHAP value of FA_con at less than 40% content is not obvious, and even up to 20% shows an increasing trend. This indicates that the flexural strength of concrete peaks at around 20% of FA_con content. For SF_con, its SHAP value appears to show fluctuations below 30%. and a smaller peak occurs around 10% and 30%, respectively. Subsequently, when the content of S_con exceeds 30%, the value decline. Therefore, combining the numerical changes of the SHAP value of S_con in several content zones, it can be concluded that the effect of S_con on the flexural strength of concrete may have peaks at 10% and 30% when the content is small. However, when the content of S_con exceeds 30%, the flexural strength decreases gradually. As for the characteristic parameter SF_con, when its content is below 18%, the value presents a fluctuating growth tendency. When the value of SF_con exceeds 18%, the trend is downward. The above shows that the maximum value of flexural strength of concrete may occur when the amount of silica fume in the cementitious material is 20%.3 and 400 kg/m3, indicating that the slag and cement interactive intervals are less than FA, and there is a certain effect on the flexural strength of concrete in this interval. In Fig. 3. This indicates that the interaction interval between silica fume and cement is mainly concentrated in the interval when the cement content is small, and silica fume will have an important effect on the flexural strength of concrete in this interval.In order to analyze in depth the effect of composite cementitious materials on the flexural strength of concrete when three supplementary cementitious materials act together with cement, and to clarify the interval of different supplementary cementitious materials acting on cement content. In this study, the SHAP values of the three supplementary cementitious materials were analyzed in combination with the SHAP values of the cement, the interactions were analyzed as shown in Fig. The LR model is the poorest predictor of flexural strength for concrete with supplementary cementitious materials. The XGB model has a higher prediction accuracy than the RF model. The XGB model is recommended for predicting the flexural strength of concrete with cementitious admixtures.Among the characteristic parameters that affect the flexural strength of concrete with supplementary cementitious materials, the highest degree of correlation with the predicted results is the water-binder ratio, followed by the curing age. The weakest correlation with the predicted results was the admixture of silica fume and slag.Water-cement ratio and age of curing have the greatest influence on flexural strength. The water-cement ratio is negatively correlated with flexural strength, while the age of maintenance is positively correlated. The relationship between aggregate content and flexural strength showed a positive correlation followed by a negative correlation. The relationship between flexural strength and cement content was similar to that of aggregate content. The effect of the three supplementary cementitious materials on the flexural strength of concrete can be summarized as the correlation with flexural strength fluctuates at small admixtures  and there is a positive correlation with the optimum admixture. However, the correlation becomes significantly negative at dosing levels greater than the above.3 and 400 kg/m3. Silica fume has an important role in low cement content.In predicting the flexural strength of concrete, different supplementary cementitious materials interact with cement in different admixture intervals. Fly ash can act in the whole blending interval of cement. Slag has an important role between cement h content of 200 kg/mFor the flexural strength of concrete containing supplementary cementitious materials, prediction studies were carried out using three machine learning models. The parameters were analyzed based on SHAP model, with the following main conclusions:


Antibiotic overuse poses a critical global health concern, especially in low- and middle-income countries (LMICs) where access to quality healthcare and effective regulatory frameworks often fall short. This issue necessitates a thorough examination of the factors contributing to antibiotic overuse in LMICs, including weak healthcare infrastructure, limited access to quality services, and deficiencies in diagnostic capabilities. To address these challenges, regulatory frameworks should be implemented to restrict non-prescription sales, and accessible point-of-care diagnostic tools must be emphasized. Furthermore, the establishment of effective stewardship programs, the expanded use of vaccines, and the promotion of health systems, hygiene, and sanitation are all crucial components in combating antibiotic overuse. A comprehensive approach that involves collaboration among healthcare professionals, policymakers, researchers, and educators is essential for success. Improving healthcare infrastructure, enhancing access to quality services, and strengthening diagnostic capabilities are paramount. Equally important are education and awareness initiatives to promote responsible antibiotic use, the implementation of regulatory measures, the wider utilization of vaccines, and international cooperation to tackle the challenges of antibiotic overuse in LMICs. Antibiotic overuse entails the inappropriate and excessive utilization of antibiotics, encompassing unwarranted prescriptions and administration, as well as the mishandling and excessive consumption of these vital medications through self-medication or leftover usage ,2. The oThis study aims to explore the complexities of antibiotic overuse in LMICs, highlighting their unique challenges and proposing strategies to tackle the problem. By advocating for global collaboration, the article seeks to combat antibiotic overuse and protect the effectiveness of antibiotics for future generations.Over the last few decades, antibiotic consumption patterns in LMICs have displayed a notable upward trend. A multinational survey that analyzed antibiotic consumption across 76 countries from 2000 to 2015 exposed a significant global increase of 65%. This surge was primarily fueled by a remarkable upswing in LMICs, which experienced a striking rise of 114% .The escalating use of antibiotics in LMICs underscores a troubling pattern of their misapplication. A noteworthy concern is the substantial uptick in the consumption of antibiotics labeled as “Watch” in the WHO’s framework. These antibiotics carry a higher risk of resistance development and include fluoroquinolones, macrolides, carbapenems, and glycopeptides. Worryingly, these crucial antibiotics are frequently prescribed and obtained without proper prescriptions in LMICs. Global data spanning from 2000 to 2015 expose a staggering 90.9% surge in the consumption of “Watch” antibiotics, with a far more disconcerting 164% surge witnessed in LMICs. WHO advocates that a minimum of 60% of all antibiotics used belong to the “Access” group, comprising affordable, narrow-spectrum agents. Regrettably, an increasing number of countries are failing to meet this target. In 2015, out of 76 countries, 42 displayed lower proportions of “Access” antibiotics ,5,6,7. FThe COVID-19 pandemic has exacerbated the problem of excessive antibiotic usage, increasing worries about the swift emergence and spread of bacterial strains that are resistant to antibiotics . In IndiIn LMICs, the overuse of antibiotics is propelled by an intricate interplay of factors that collectively contribute to elevated rates of antibiotic consumption .Comprehending these underlying drivers is imperative for formulating effective strategies to tackle this issue. Many LMICs grapple with limited access to healthcare and facilities that are understaffed and lack adequate resources ,26,27. CIn LMICs, antibiotics are easily obtainable without requiring a prescription, primarily due to the absence of stringent regulations or the insufficient enforcement of existing laws ,45. NeveNeisseria gonorrhoeae and Chlamydia trachomatis, necessitating the use of two distinct antibiotics [Diagnostic uncertainty stands as a significant factor driving antibiotic overuse in primary care, impacting both HICs and LMICs . Point-oibiotics . In LMICibiotics . POC tesibiotics . CRP, whibiotics . Rapid aibiotics . Recent ibiotics . Novel tAntimicrobial stewardship programs effectively cut antibiotic use in both hospital and non-hospital environments . In HICsStreptococcus pneumoniae, a major cause of pneumonia, is an illustrative example, causing significant global morbidity and mortality [Salmonella enterica serovar Typhi, which is resistant to chloramphenicol, ampicillin, co-trimoxazole, fluoroquinolones, and third-generation cephalosporins, thus leaving very limited options for treating affected individuals [Escherichia and Klebsiella spp [Neisseria gonorrhoeae [® meningococcal vaccine has demonstrated some protective effects against gonorrhea. It is currently undergoing extensive clinical trials for this purpose [The threat of AMR and the rapid emergence of new pathogens highlights the importance of vaccines. With multidrug-resistant bacteria spreading and limited treatment options ,90, vaccortality . The intortality . A comprortality . Rotavirortality ,14,98. Tortality . Maternaortality ,101,102.ortality ,104. Sincycline) ,106. Theella spp ,108. Pakella spp . TCV is ella spp . In a 20ella spp . A GAVI-ella spp ,113,114.orrhoeae ,116. For purpose . As we a purpose ,119,120.In areas where health systems are fragile, overburdened, or hard to reach, patients frequently turn to self-care or consult informal healthcare providers due to the restricted availability of formal medical services. Numerous studies conducted in low- and middle-income countries (LMICs) have demonstrated that in situations where healthcare access is limited, antibiotics are often utilized without the supervision of a healthcare expert. For example, in Vietnam, 55.2% of outpatient antibiotics were distributed without a prescription, while the corresponding figure in Bangladesh was 45.7% . MoreoveTo tackle antibiotic overuse in LMICs, we need a comprehensive approach. This involves improving healthcare infrastructure, educating the public about proper antibiotic use, regulating non-prescription sales, training informal healthcare workers, using accessible diagnostics, and promoting vaccines. A global effort is crucial to address these challenges, ensure sustainable changes, and preserve antibiotic effectiveness against infectious diseases.Addressing antibiotic overuse in LMICs is complex but crucial. Start by improving healthcare infrastructure, including training and equipping professionals. Rather than only restricting access, address infrastructural weaknesses that drive misuse. Regulations are needed, but must consider disparities in urban and rural areas. Involve informal healthcare workers through training and prescribing permissions. Use affordable POC diagnostic tools integrated into algorithms to guide informed decisions. Stewardship programs require IT investments for effective tracking. Educate healthcare providers and the public, including non-traditional groups, using resources like the WHO’s AWaRe Antibiotic Book. Expand vaccine programs, focusing on accessibility and uptake to reduce infections and antibiotic use. Collaborative efforts are key.


The high adiabatic temperature rise and low heat dissipation rate of mass concrete will promote rapid hydration of the cementitious material and rapid consumption of water from the concrete pores, which may significantly accelerate the development of concrete autogenous shrinkage. In this study, the effect of the water-binder ratio on the autogenous shrinkage of C50 concrete mixed with MgO expansion agent (MEA) was explained with respect to mechanical properties, pore structure, degree of hydration, and micromorphology of the concrete based on a variable temperature curing chamber. The results show that the high temperature rise within the mass concrete accelerates the development of early (14 d) autogenous shrinkage of the concrete, and that the smaller the water-binder ratio, the greater the autogenous shrinkage of the concrete. With the addition of 8 wt% MEA, the autogenous shrinkage of concrete can be effectively compensated. The larger the water-binder ratio, the higher the degree of MgO hydration, and in terms of the compensation effect of autogenous shrinkage, the best performance is achieved at a water-binder ratio of 0.36. This study provides a data reference for the determination of the water-binder ratio in similar projects with MEA. High-strength concrete is being used more widely due to the increasing demands of modern construction ,2. CompaA great deal of research has been carried out and solutions have been proposed, both nationally and internationally, on how to reduce the autogenous shrinkage of concrete ,12,13. TUnder normal temperature conditions, the use of MEA to compensate for autogenous shrinkage of concrete has been well documented ,25. HoweThis study is based on a large volume straight wall concrete project, using the same concrete mix ratio as that of the straight wall on site (8 wt% of MEA). Through a simulation of the site temperature history (high temperature peak and low cooling rate), the effect of the water-binder ratio on the autogenous shrinkage of concrete with MEA under the variable working temperature conditions was investigated, in order to provide a basis for the selection of the water-binder ratio of concrete for engineering structures. In this research, Ordinary Portland cement (OPC) was provided by Jiangnan Onoda Cement Co., Ltd. . Fly Ash (FA) was supplied from Nanjing, and blast furnace slag (BFS) was provided by Mabel Ltd. , which were used as the supplementary cementitious materials. The MEA was supplied by Nanjing Subote New Material Co., Ltd. , of which the reactivity value was 200 s. Its reactivity was estimated by the citric acid method in accordance with Chinese standard CBMF-2017 . The cheFour concrete mixtures (numbered from C1 to C4) containing 8 wt% MEA are shown in A variable temperature curing chamber was used to simulate the history of changes in the central temperature of straight walls in engineering. According to Chinese standard GB/T 50081-2019 , the conConsidering that the concrete of the straight walls in the project was in a sealed state before the early demolding, which would have exacerbated the autogenous drying shrinkage, the autogenous deformation test was performed. The test for autogenous shrinkage of concrete is carried out using the buried strain gauge method with reference to SL/L 352-2020 . After t2 atmosphere, heated from room temperature to 950 °C.At 1 d, 3 d, and 7 d, the mixtures of concrete without sand were analyzed to calculate the hydration of magnesium oxide. After being cut into pieces, the samples were soaked in the anhydrous ethanol for a week for the purpose of terminating their hydration. Then, the samples were placed in a vacuum drying oven at 60 °C until the mass was stable. After, those dried samples were ground into powders of no more than 0.080 μm. The powder samples were tested using NETZSCH STA 449F1 thermogravimetry under a NThe pore structure of concrete specimens was tested using a mercury intrusion porosimeter (MIP). According to the sample preparation requirements, the samples maintained in the variable temperature oven were taken out. Concrete specimens were cut into 3~5 mm pieces and soaked in anhydrous ethanol, which was aimed at terminating the hydration of samples. Afterward, the samples were placed in an oven at the temperature of 60 °C until the mass was stable.2. Based on Mo [2 and the hydration degree of MgO can be calculated by Equations (1) and (2):ed on Mo , the qua2 and the hydration degree of MgO in the samples. It is clear that there is a rapid increase in the hydration degree of MgO during the first 3 d. The water-binder ratios  are 53.1%, 52.3%, 55.2%, and 67.4%, respectively, which are highly dependent on the curing temperature at which the specimens are maintained, once again confirming the temperature sensitivity of the MEA and that high temperatures accelerate the hydration of MgO. The hydration degrees of MgO in concrete with different water-binder ratios are relatively close at 3 d, which is probably attributable to the fact that there is sufficient water inside the concrete in the early stages and MgO competes with cement for water. When at 7 d, there is a notable difference between different water-binder ratios. The hydration degrees of MgO in the concrete with the water-binder ratios of 0.40, 0.36, and 0.40 are 72.6%, 66.9%, and 62.8%, respectively, whereas the hydration degree is only 58.9% when the water-binder ratio is 0.28. Combined with the changes of humidity in +, which allows more Mg(OH)2 products to grow inside the pores, thus changing the pore size distribution inside the pastes and refining the pore size.2 crystals are mainly in the form of flakes of different sizes, which grow near the MgO particles. Ca2+ has an inhibitory effect on the diffusion of Mg2+ and promotes the growth of Mg(OH)2; therefore, Mg(OH)2 crystals generally grow near Ca(OH)2 crystals. The lamellar Mg (OH)2 crystals in 2. The thermal analysis shows that there is little difference in the degree of hydration of MgO in concrete with different water-binder ratios at 3 d. However, at 7 d, the hydration degree of MgO in concrete with a water-binder ratio of 0.40 is 72.6% compared to 58.9% with a water-binder ratio of 0.28. Sufficient water is supplied to MgO to produce Mg (OH)2, which counteracts the pore pressure and is the key to compensating the autogenous shrinkage of concrete. Meanwhile, Ca2+ has an inhibitory effect on the diffusion of Mg2+, which promotes the nucleation and growth of Mg (OH)2. Thus, Mg (OH)2 crystals mostly grow overlappingly in pores not far from the MgO particles. Moreover, the higher the water-binder ratio, the denser the hydration product of MgO. The early arrival of the hydration period of MgO allows the crystalline growth pressure of the Mg (OH)2 crystals to resist the early shrinkage deformation of the concrete. However, the autogenous deformation of mass concrete in practical projects is more complex, as the restraint of reinforcement, the large temperature difference between day and night, and the method of construction all affect the autogenous shrinkage of concrete. Increasing or changing the water-binder ratio alone will not completely overcome the problem of autogenous deformation of concrete and needs to be carried out in cooperation with other effective measures according to the actual situation of the project at the time. This study was carried out based on a large volume of straight wall concrete and is intended to provide a reference for similar projects with MEA.Bulk high-strength concrete generally has a high adiabatic temperature rise due to the great amount of cementitious material and the slow dissipation of heat from the concrete. In large volume straight wall concrete projects, temperatures in the center of the concrete can reach over 70 °C (and even 80 °C) and do not drop to room temperature until 14 d. The high temperature changes within the bulk straight wall concrete not only accelerate the development of autogenous concrete deformation but also promote the hydration of MgO. Although the addition of MEA mitigates the autogenous shrinkage of the concrete, the effect of different water-binder ratios on the deformation of concrete under variable temperature conditions varies slightly. Compared to concrete with a water-binder ratio of 0.28, an increased water-binder ratio not only reduces the autogenous shrinkage of the concrete itself but also contributes more to the hydration of MgO and the production of more Mg (OH)The internal temperature variations of C50 bulk straight wall concrete structures in practical projects were simulated in the laboratory. On this basis, the influence of different water-binder ratios on the compressive strength, autogenous shrinkage, pore size, and micromorphology of concrete with MEA was studied. The key conclusions are the following:The hydration process of MgO is accelerated under variable temperature curing. The addition of 8 wt% MEA reduces the compressive strength of the concrete, but the effect is minimal (no more than 5 MPa). In this experiment, the compressive strength of the concrete at 7 d can reach 85% or more at 28 d. High temperature accelerates the early self-shrinkage of concrete, especially within 7 d. Increasing the water-binder ratio can reduce the autogenous shrinkage of concrete. When the water-binder ratio is 0.40, the concrete deformation is slightly expanded. Compared to the reference group without MEA, the best effect of compensating for autogenous shrinkage is achieved by adding 8% MEA with a water-binder ratio of 0.36. Therefore, in actual projects, the water-binder ratio can be relaxed to 0.36 or even 0.40 under the premise of ensuring strength.2 crystals, appear as lamellar in the cement system, growing mainly in the pores not far from the MgO particles and overlapping each other. As the water-binder ratio increases, the MgO hydrates more and the Mg(OH)2 crystals become denser, which fills the pores better and counteracts the autogenous shrinkage of the concrete.At high temperatures, the hydration product of MgO, Mg(OH)


Escherichia coli. EVs were characterized using immunoblotting, nanoparticle tracking analysis, and transmission electron microscopy. Several beta-lactam antibiotics caused significantly more EV release, while quinolone and aminoglycosides caused relatively less vesiculation. Further study is warranted to corroborate the correlation between an antibiotic’s mechanism of action and its effect on EV release, but these results underline the importance of antibiotic choice when treating sepsis patients.Sepsis, a leading cause of death in hospitals, can be defined as a dysregulated host inflammatory response to infection, which can lead to tissue damage, organ failure, and cardiovascular complications. Although there is no cure for sepsis, the condition is typically managed with broad spectrum antibiotics to eliminate any potential bacterial source of infection. However, a potential side-effect of antibiotic treatment is the enhanced release of bacterial extracellular vesicles (BEVs). BEVs are membrane-bound nanoparticles produced by a variety of mechanisms, one of which includes the pinching-off of the outer membrane (in Gram-negative bacteria) to enclose proteins and other biological molecules for transport and intercellular communication. Some of the Gram-negative EV cargo, including Peptidoglycan associated lipoprotein  and Outer membrane protein A (OmpA), have been shown to induce both acute and chronic inflammation in host tissue. We hypothesize that antibiotic concentration and its mechanism of action can have an effect on the amount of released BEVs, which could potentially exacerbate the host inflammatory response. In this study, we evaluated nine clinically relevant antibiotics for their effect on EV release from  According to the International Society for Extracellular Vesicles (ISEV), extracellular vesicles (EVs) are membrane-enclosed nanobodies that are naturally released from all cell types and lack a functional nucleus . BacteriUnderstanding how and why antibiotics enhance the release of bacterial EVs is crucial, especially in the context of sepsis patients who often receive broad-spectrum antibiotics as a first line of treatment. OMVs containing LPS, virulence factors, adhesins, and lipoproteins have been implicated in initiating inflammation during the transition from infection to sepsis –5]. The. The5]. The immunomodulatory molecules contained within OMVs, including LPS and other outer membrane proteins, are thought to interact with host cells through several different mechanisms, such as activating host immune cells via TLRs , triggering the release of pro-and anti-inflammatory cytokines, and delivering bacterial content into host cells –8] Addi Addi8] AEscherichia coli (E. coli), more so than other antibiotics. We developed this hypothesis, in part, based on our own studies, as well as other studies that have looked at the effect of antibiotics on GN BEV release . Fo. FoEscheoduction . A thirdO157:H7) .E. coli (E. coli K1 RS218). These antibiotics are commonly used to treat sepsis patients at the University of Rochester Medical Center : six beta-lactam antibiotics , two aminoglycoside antibiotics (tobramycin and amikacin), and one quinolone antibiotic (ciprofloxacin). A brief summary of each antibiotic’s mechanism of action is described in In this study, we tested nine clinically relevant antibiotics for their effect on EV release from a clinical strain of E. coli strain K1 RS218). For the first set of experiments, we considered the general intravenous dosages for each antibiotic commonly used by physicians at URMC. The “clinical concentrations” were determined for each antibiotic to be roughly proportional to the clinical dosage, as described in the methods section and in We used two different strategies to determine the antibiotic concentrations for our experiments. For the first set of experiments, we determined the minimum inhibitory concentration (MIC) for each antibiotic , which iE. coli cells, post-incubation with either clinical concentrations or 2MIC of antibiotics . The isolated EVs were quantified using immunoblotting with antibodies to E. coli peptidoglycan associated lipoprotein  and outer membrane protein A (OmpA). In some cases, particularly when no antibiotic was used, only faint bands were detected, in which case we assumed that although EVs were likely produced, the amount of isolated EVs was below our limit of detection. Pal and OmpA band volumes for both sets of experiments are shown in EVs were isolated from Nanoparticle Tracking Analysis (NTA) is a technique used to measure the size distribution and concentration (particle/mL) of nanoparticles in a liquid sample. NTA employs laser light scattering to individually track and analyze the Brownian motion of nanoparticles, estimating the size of the particles based on their diffusion properties. Results from the NTA experiments are shown in All BEV samples were prepared as described above for immunoblotting and NTA and then imaged with transmission electron microscopy (TEM). We selected a subset of antibiotics  to test for their effect on BEV release. As expected, BEVs have a distinct bilayer membrane and sometimes exhibit a puckering effect, as is a common side effect from the TEM staining/drying process  and 4. WE. coli in the presence of antibiotics versus control (no antibiotics), according to Pal band volume measurements. As seen in E. coli between 3 and 5-fold compared to control, while the one quinolone tested (ciprofloxacin) exhibited a small increase in BEV release compared to control. Aminoglycosides (tobramycin and amikacin) averaged similar BEV counts as seen for the control sample, suggesting that the aminoglycoside antibiotics do not enhance BEV production. Moreover, beta-lactam antibiotics induced about 2 to 4-fold more BEV release compared to the other groups, while the quinolone induced only 1 to 2-fold more BEVs compared to aminoglycosides  have been implicated in both inflammatory and anti-inflammatory host responses and are thought to contribute to disease pathogenesis, due largely to their cargo, which can include toxic, virulent, and inflammatory molecules. Because of their inflammatory contributions, BEVs have been studied as potential therapeutic targets, vaccine delivery systems, and diagnostic biomarkers .E. coli. We measured BEV release using two approaches: quantification of two protein antigens commonly found in E. coli BEVs, peptidoglycan-associated lipoprotein  and outer membrane protein A (OmpA), using immunoblotting and particle counts using nanoparticle tracking analysis (NTA). We also characterized the BEVs using transmission electron microscopy (TEM). Although there was some variability in the data, the results from these approaches converged on several common themes.Here, we describe our investigation into the effect of clinically relevant antibiotics, at two biologically-significant concentrations, on BEV release from E. coli bacteria are incubated with antibiotics at 2MIC or clinical concentrations, beta-lactam antibiotics induce approximately 4-fold the amount of BEV release compared to the aminoglycosides, 2 to 3-fold compared to the quinolone antibiotic, and 3 to 5-fold compared to no antibiotics , perhaps resulting in our overestimation of ceftriaxone’s MIC [E. coli to be closer to μg/mL,15-fold lower than our estimated 125 μg/mL [E. coli produces BEVs at levels comparable with the other beta-lactam antibiotics. We also noticed that piperacillin produced lower BEV levels compared to the other beta-lactam antibiotics. Piperacillin is often used in the clinic in combination with tazobactam, a beta-lactamase inhibitor, suggesting that the activity of piperacillin alone (as used in this study) was likely inhibited by beta-lactamases excreted by the E. coli bacteria [A fourth common theme was that ceftriaxone was always among the greatest BEV-producing antibiotics. Minimum inhibitory concentrations of antibiotics were determined by incubating ne’s MIC . The TEM25 μg/mL . As seenbacteria .The last common theme that we drew from this study was that administering antibiotic doses beyond twice their minimum inhibitory concentrations 2MIC) leads to extensive BEV release. Specifically, we observed much greater BEV production with clinical concentrations of ertapenem, meropenem, and cefepime compared to 2MIC of the same antibiotics, where clinical concentrations were estimated to be >100-fold higher than the 2MICs  and 2. TMIC leadsIn most sepsis cases where antibiotics are the first line of treatment, the results of this study emphasize the intricate and complex nature of antibiotic dosing, considering the potential impact of BEVs and their ability to contribute to inflammation and pathogenicity. However, we acknowledge that most sepsis patients are prescribed broad-spectrum antibiotics, because the specific bacterial cause of infection is unknown, further complicating matters and requiring high doses of antibiotics in order to eliminate a broad range of possible bacterial pathogens. However, our study highlights a potential unfavorable outcome of this treatment strategy, which is the enhancement of BEV production, which can contribute to or exacerbate sepsis-related inflammation or, due to BEV’s ability to enter deep into human tissue, result in longer-term chronic responses to infection and inflammatory pathologies.E. coli strain K1 RS218 was a gift from Dr. Kwang Sik Kim . E. coli were cultured in LB broth, shaking between 120-200rpm and incubated at 37°C.E. coli was cultured in LB overnight. The growth was used to inoculate individual cultures (in test tubes) with serially diluted antibiotics in LB. A negative control culture contained no antibiotic. The cultures were incubated overnight at 37°C, shaking at 180rpm, and then checked visually for the lowest concentration of antibiotic with no visible cloudiness.Six beta-lactam antibiotics, two aminoglycosides, and one quinolone antibiotic were selected based on their clinical significance, accessibility, and usage to treat sepsis patients at URMC. The minimum inhibitory concentration (MIC) of each antimicrobial agent was determined using the broth-dilution assay. In summary, To estimate the “clinical concentrations” of antibiotics, we used an average weight of 70 kg per person. In the clinic, a loading dose of 3mg/kg of tobramycin is given initially, followed by maintenance dosing to reach a peak serum concentration of 7-10 μg/ml. Therefore, we estimated 210 mg of Tobramycin was given to the patient every 8 hours (3mg/kg * 70kg = 210mg), or 630mg given to the patient per day. We assumed 630mg of tobramycin was administered per day to get a peak serum concentration of 10 μg/ml. Therefore, all clinical concentrations were calculated using the following formula: X grams administered per day divided by 0.63 g x 10 μg/ml. We recognize that our “clinical concentrations” may be over-estimated, since they were based on a total tobramycin dose of 630 mg over 24 hours, which would be high for a 70 kg person. Nevertheless, these doses were normalized across all drugs tested and therefore apply equally to all antibiotic classes used. Therefore, our comparisons are valid and provide proof of principle that BEV release depends on antibiotic class.E. coli were cultured on LB agar at 37°C overnight; colonies from the plate were used to inoculate a 50 mL growth, which was cultured overnight at 37°C, shaking at 180 rpm. The small culture was used to inoculate two larger cultures (2×300mL), which were grown to log phase . The two 300mL cultures were mixed and then aliquoted into ten sterilized 125mL flasks (50mL of culture in each flask). All antibiotic solutions were prepared, as described above at either 2MIC or their calculated clinical concentration, and then aliquoted into the corresponding flask. The E. coli cultures were incubated with antibiotic  for 3.5 hours . Cells were pelleted for 15 minutes at 5,000xg, and the supernatants were syringe filtered using 0.45μm filters and then concentrated from ~50mL to ~30 mL using 50kDa MWCO Amicon filters (Millipore). Extracellular vesicles were isolated by ultracentrifugation , and resuspended in 200μl of phosphate buffered saline (PBS).™ West Femto Maximum Sensitivity Substrate (ThermoFisher) and imaged using the BioRad ChemiDoc Imaging System. Band volumes were quantified using Biorad’s Quantity One software package.Samples were analyzed using standard SDS-PAGE  and immunoblotting techniques. For immunoblotting, we used rabbit polyclonal antibody anti-OmpA  or unpurified anti-Pal antisera from mice inoculated with purified recombinant non-lipidated Pal protein . Immunoblots were developed using SuperSignalAll experiments were performed four or six times , and the bar graphs are presented as mean values with error bars as standard error of the mean (SEM), calculated using GraphPad Prism 10.0 . When the experiments were performed, all antibiotic samples were prepared at the same time (and from the same culture), but the BEV samples were run on two gels. Therefore, we normalized the band volumes from one gel to the other using the imipenem sample or purified Pal protein, where those samples were run on both gels and then normalized to be the same volume.The BEVs were isolated from cultures grown with 2MIC of ceftriaxone, cefepime, amikacin, ciprofloxacin, or no antibiotic (control). 200 mesh copper grids coated with formvar/carbon film were glow discharged for 30s at 30 mA in a PELCO Easiglow prior to 3 uLs of the liquid BEV sample being applied for 30s. Excess sample was wicked away and grids were exposed to three 15 uL washes with molecular grade water prior to negative staining with two applications of 10 μL of filtered 0.75% uranyl formate, with wicking of excess fluid using hardened Whatman 50 filter paper, between steps. The grids were allowed to dry prior to examination on a Talos 120C transmission electron microscope equipped with a CETA 16 megapixel camera (Thermo Fisher) for image capture using TIA (Thermo Fisher).Nanoparticle size distributions were assessed using nanoparticle tracking analysis, equipped with a sCMOS camera, 532 nm green laser, and a 565 nm long pass filter . For clinical concentrations, the beta-lactam samples were diluted 1:1000 in PBS. For 2MIC, beta-lactam samples were diluted 1:100 in PBS, and all other samples were diluted 1:10 in PBS. Three measurements of each sample were performed for 30 seconds each, with a camera level of 13 and detection threshold of 5, and average particle concentrations were reported after taking the dilution factors into account.1


In contrast, nitrofurantoin resistance (NitR) requires the inactivation of two chromosomally encoded nitroreductases: nfsA and nfsB. The difference in antimicrobial resistance (AMR) evolution is reflected in community surveillance data: NitR incidence = ∼10% and for TriR > 30%. Longitudinal clinical UTI trials provide a unique opportunity to monitor in situ evolution of AMR and correlate its appearance to trial outcomes and the impact on uropathogens.The mainstay treatments for urinary tract infections (UTIs) are nitrofurantoin and trimethoprim. The common route to acquire trimethoprim resistance (TriR) is via horizontal transfer of the trimethoprim-insensitive dihydrofolate reductase: Escherichia coli isolates from patients participating in the clinical trials: AnTIC and ALTAR. AnTIC was an open label randomized trial assessing the efficacy of antibiotic prophylaxis use in clean intermittent self-catheterizing patients. ALTAR compared the efficacy of the non-antibiotic alternative methenamine hippurate to antibiotic prophylaxis to treat recurrent UTIs.To explore the in situ AMR evolution and its impact in E. coli used general microbiology techniques, bioinformatic genome analysis and genetics to model known AMR mutations in susceptible E. coli strains.The investigation of the evolution of nitrofurantoin and trimethoprim resistance in E. coli trial isolates was driven by 14 out of ∼45 known dfrA allelic variants; the most common being dfrA1 and dfrA17. Growth analysis identified an allelic bias when strains were exposed to sub-MIC concentrations of trimethoprim. Growth rate analysis identified a 2%–10% slower doubling time for nitrofurantoin-resistant strains: NitS: 20.8 ± 0.7 min compared to NitR: 23 ± 0.8 min. Statistically, these data suggested no fitness advantage of evolved strains compared to the sensitive predecessor . Genetic manipulation of E. coli to mimic NitR evolution, however, supported a selective advantage.Trimethoprim resistance amongst E. coli to UTI-related antibiotics. Correlation of nitrofurantoin response to pharmacokinetic data suggests that the low incidence of E. coli NitR is driven by selection not fitness. However, fitness correlates to dfrA allele carriage and could potentially be exploited to benefit the use of trimethoprim if other antibiotics are impeded by AMR.Longitudinal sampling during antibiotic based clinical trials has provided a new perspective to the response of


Generic medications are bioequivalent to brand-name medications, but the quality and purity of generic medications are still debatable. The aim of this study was to compare the generic product of metformin (MET) to its branded counterpart using pure MET powder as a reference. Quality control tablet assessment and in vitro evaluation of drug release were carried out in various pH media. Additionally, several analytical methods and thermal techniques were used, namely differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), and confocal Raman microscopy. The results showed a significant difference between the two products. In terms of friability assessment, mean resistance force, and tablet disintegration, the generic MET product showed significant weight loss, higher mean resistance force, longer disintegration time, and a slower rate of drug release. In addition, DSC and TGA showed that the generic product had the lowest melting point and the least weight loss compared to the branded product and pure powder. XRD and SEM demonstrated some changes in the crystallinity structure of the molecule particles for the generic product. Additionally, FTIR and confocal Raman revealed the same peaks and band shifts in all samples, but with differences in the intensity for the generic tablet only. The observed differences could be due to the use of different excipients in the generic product. The possibility of forming a eutectic mixture between the polymeric excipient and metformin in the generic tablet was presumed, which might be attributed to alterations in the physicochemical properties of the drug molecule in the generic product. In conclusion, using different excipients might have a significant effect on the physicochemical properties of drugs in generic formulations, leading to significant changes in drug release behavior. In accordance with Food and Drug Administration (FDA) regulations and specifications , genericThe immediate-release generic product of MET was chosen as the model generic drug in this study. The generic MET product was compared to the brand-name MET product using pure MET powder as a reference to identify any potential differences.N-dimethylimidodicarbonicarbonidediamide, is a first-line medication for type 2 diabetes mellitus [4H11N5, and it has a molecular mass of 165.6 g/mol and a melting point range of 223–226 °C [MET, also known as N, mellitus ,11,12. T3–226 °C . Accordi3–226 °C ,15. Alth3–226 °C ,16.Several research studies have suggested the possibility of excipient interference between the active ingredient and excipients in generic products ,18,19,20A number of analytical techniques have been found to be essential in the evaluation of potential variations between generic and branded medications ,28,29, sThe aim of this work was to investigate possible differences between the branded drug product of MET tablets (850 mg) and the generic products of MET tablets (850 mg) using pure MET crystal powder as a reference for drug identification. Accordingly, a series of experiments was conducted to determine the influence of different incorporated excipients on the physicochemical properties of generic MET tablets. To achieve these objectives, a variety of analytical methods and thermal techniques were used, namely DSC, TGA, XRD, SEM, FTIR, and confocal Raman microscopy. In addition, the in vitro drug release rate was evaluated, and quality control tests for the tablets were determined. This study was the first of its kind to investigate the potential causes of issues associated with generic MET products. In this study, a number of thermal and analytical techniques were used as scanning tools prior to bioequivalence assessment ,39.p < 0.05). The mean resistance force was significantly higher for the generic MET product (450.90 N ± 53.24 N) compared to the branded MET product (299.10 N ± 44.71 N) (p < 0.05). The generic MET product took 5 min longer to completely disintegrate compared to the branded MET product, which is significantly higher (p < 0.05).Quality control tests showed similarities between the generic MET product and the branded MET product tablets (850 mg), except for friability, mean resistance force, and disintegration time for the two products, as shown in p < 0.05). It is evident that the release rate of the generic MET product was dependent on the pH media, as compared to the branded MET product, which was pH-independent [The drug release rate for the generic MET product (MET Tablet Generic) was found to be lower than that of the branded MET product in distilled water (DW), as illustrated in ependent .p < 0.05).p < 0.05). As shown in p < 0.05), equaling 4.936 mg. The onset temperature of weight loss also varied among the samples as shown in Tonset) temperature indicate that some differences occurred in the physical properties of the generic MET product.The TGA profiles for the three samples  showed significant differences in terms of weight loss  is likely due to differences in the incorporated excipients in the formulation, as reported in various research studies ,49,50,51The lower heat absorbed and lower amount of weight lost by the generic MET product compared to the branded MET product, as shown in the DSC and TGA thermal profiles, could be due to several possibilities, as has been reported in other research studies ,54,55. OAnother possibility could be due to the formation of a eutectic mixture between hydrophilic polymeric components, such as PEG or starch, and the active ingredient MET , which mThe observed decrease in the intensity of the XRD peaks for the generic MET product compared to the branded MET product might indicate changes in the crystal structure of the generic MET product. This alteration might be related to differences in the incorporated excipients in the two products, as suggested by previous research studies ,60. A pr−1, 1625 cm−1, and 3170 cm−1 in FTIR, respectively, whereas they appeared at shift numbers 1040 cm−1, 1650 cm−1, and 2850 cm−1 in confocal Raman for all three products. The existence of these functional groups confirms the presence of the MET compound in the formulation of both products, yet the intensity of the peaks varied between the branded MET product and the generic MET product. The variations in peak intensities observed in the FTIR and Raman spectra of the three products can be attributed to differences in the amount of active ingredient dispersed in the three samples [Several main bands in FTIR and confocal Raman were similar for all samples but with different peak intensities. For instance, the C-N, C=N, and CH functional groups were indicated by the presence of wave numbers 1571 cm samples ,62,63. T samples ,62,63.The brand-name MET tablets (850 mg) and the generic MET tablets (850 mg) were purchased from Boots Pharmacy . The pure MET powder was obtained from Sigma-Aldrich .A sensitive digital scale  was used to weigh a total of 20 tablets for each product. The tablets were individually weighed to determine their average weight. The weighing procedure followed the guidelines and standards set by the United States Pharmacopeia (USP) , ensurinThe friability test was conducted in accordance with the standards and specifications set by the USP . For eacThe mean resistance force of the two products was determined using a TBH-225 TD hardness tester . Ten tablets each of the branded MET product and the generic MET product were randomly selected for the hardness assessment. The standard deviation was calculated for each product, and the mean resistance force of the tablets was measured. The mean resistance force test was performed in accordance with the guidelines and specifications set by the USP .n = 6) for each product to ensure the accuracy and precision of the assessment.The chemical composition of the two products was determined by weighing and triturating 20 tablets from each product. A solution of MET was then prepared by diluting 100 mg of the sample in 100 mL of distilled water (DW). The prepared solution was further diluted and filtered to achieve a final concentration of 100 µg/mL. The concentration of the solution was measured using spectrophotometry at an ultraviolet (UV) wavelength of 233 nm, and the entire process was conducted six times . The disintegration test was performed using DW at a fixed temperature of 37 °C ± 0.5 °C for a duration of 30 min. Six tablets were randomly selected from each product and subjected to the disintegration test. The disintegration time of all the tablets was accurately recorded for analysis. The assessment was performed in accordance with the specifications set by the USP.n = 6). The in vitro dissolution evaluation was conducted in accordance with the specifications set by the USP.In vitro drug release evaluations for both products were performed using a Dissolution Apparatus II model Dis 8000 . The apparatus was operated at a speed of 100 RPM, and the temperature of the dissolution medium was maintained at 37 °C ± 0.5 °C. The in vitro dissolution evaluation was carried out using 900 mL of filtered DW, as well as three different pH media values , to simulate various physiological pH conditions. Samples of 5 mL were collected from each vessel at specific time intervals . The samples were diluted using the same incubation media, followed by filtration of the samples. The filtered samples were then analyzed using UV spectrophotometry at a wavelength of 233 nm. The experiment was conducted for six samples of each product (n = 6) to ensure the statistical validity of the results.The DSC measurements of the two products and pure MET powder were performed using a DSC-60 Plus instrument . For each product, a precise amount of 3–5 mg powder was weighed and loaded into sample pans for thermal analysis. The scanning temperature for each sample was performed between 25 and 350 °C at a rate of 10 °C per min, while a constant flow of nitrogen at 100 mL/min was maintained in a controlled environment. LabSolutions TA software was used to process and analyze the obtained results. The experiment was performed on six samples of each product (n = 6).TGA of the two products and pure MET powder was performed using a TGA-50 instrument . For each sample, 10–15 mg of powder was accurately weighed and placed in an alumina pan. The samples were scanned over a temperature range of 0 °C to 600 °C at a rate of 15 °C per min while being exposed to a nitrogen flow rate of 50 mL per min. The analysis process was closely monitored and controlled using LabSolutions TA Thermal Analysis Workstation software. To ensure the statistical validity of the results, the experiment was conducted using six samples of each product . The XRD patterns of the samples were obtained by conducting 2θ scanning within a range of 10° to 80° at a rate of 2° per min. The analysis process was carefully maintained and conducted consistently to ensure high-quality results .The morphological features of the two products and pure MET powder were examined using a JSM-6010PLUS/LA Scanning Electron Microscope . To prepare the samples for testing, a small amount was attached to the specimen holder stub using double-coated adhesive carbon tape. Before conducting the test at 20 kilovolts, a layer of gold coating was applied to the sample for 10 min using a Cressington 108 Auto Sputter Coater. The gold-coated sample was then placed in the sample stage and analyzed using InTouchScope SEM software. The process was carried out with precision to ensure the quality of the analysis.−1–450 cm−1. In order to obtain the spectra, 32 scans were conducted, and the data were processed using OMNIC 9 software to ensure the accuracy and consistency of the obtained results [To obtain the FTIR spectrum profiles of the two products and pure MET powder, a Thermo Nicolet Nexus 670 spectrometer  was utilized. The samples were first mixed with dry potassium bromide at a weight ratio of 1:100 to create pellets. The transmittance of the samples was then recorded within the range of 4000 cm results ,67.−1 to 4000 cm−1, was scanned, and the corresponding counts were recorded. The RAON-SPEC program was used to analyze all samples.A Confocal Microscope Raman/PL System  was utilized to obtain the Raman spectra for the two products and pure MET powder. To conduct Raman mapping, the sample was mounted on a glass slide and subjected to a five-sec laser exposure using a 20× objective lens. The Raman shift range of each sample, spanning from 0 cmt-test to compare the mean values of the determined variables. Differences were considered significant if p < 0.05 [The statistical analysis of variance was performed using the independent sample p < 0.05 ,69. The In conclusion, some variations between the generic MET product and the branded MET product were observed with respect to friability, mean resistance force, disintegration timing, in vitro drug release rate, thermal profile, morphological features, and peak intensities. These variations might be attributed to excipient differences in the formulation of the generic tablet. A possible interferences between excipients and active ingredients was presumed. Effect of excipients on active ingredients of MET might have an effect on the drug, resulting in a decrease in the drug release rate for the generic MET tablets.


Cyclophosphamide (CYP), methotrexate (MTX), and 5-fluorouracil (5-FU) are extensively utilized in the therapeutic management of various malignancies. It is noteworthy, however, that potential chemotherapy-related complications include the occurrence of hypothyroidism and cardiotoxicity. Metformin (MET) is a pharmacological agent for managing type 2 diabetes. It has been reported to mitigate certain toxic manifestations associated with chemotherapy. This study’s primary objective is to investigate MET’s protective effects against hypothyroidism and cardiotoxicity induced by CMF treatment. A total of forty male rats were allocated into four distinct groups, each consisting of ten rats per group. These groups were categorized as follows: saline, MET, CMF, and CMF + MET. The experimental group of rats were administered CMF via intraperitoneal injection, receiving two doses of CMF, and fed MET in their daily drinking water, with a 2.5 mg/mL concentration. Blood samples were collected into EDTA tubes for assessment of TSH, free and total (T4 and T3), troponin I, CK, and CK-MB levels utilizing Electrochemiluminescence Immunoassays (ECI). The saline and MET groups did not exhibit significant alterations in thyroid hormones or cardiotoxic biomarkers. In contrast, in the CMF group, there was a notable reduction in T4, FT4, T3, and FT3 levels but no significant changes in TSH levels; however, troponin I, CK, and CK-MB levels were notably elevated. MET co-treatment with CMF did not ameliorate these effects caused by CMF. In conclusion, CMF treatment induced hypothyroidism and cardiotoxicity in rats, but MET co-treatment did not rescue the reduction of thyroid hormones or the elevation of cardiotoxic biomarkers. Chemotherapy’s major procedure of action is generating cytotoxicity, which makes it effective against many different forms of cancer ,2. CardiCMF is a triad of chemotherapeutic agents frequently employed in synergistic regimens for the management of diverse malignancies . The effThe thyroid gland is subject to stimulation by thyroid-stimulating hormone (TSH), which is secreted by the anterior pituitary gland . This stHypothyroidism may also have negative effects on other organs, including the brain and the heart, as neuroimaging studies have revealed alterations in the brain structure and function of hypothyroid patients ,25. MoreFurthermore, it is imperative to acknowledge that cardiotoxicity represents a significant health concern, as it engenders a compromised blood flow to the various anatomical regions of the body, thereby diminishing the supply of oxygenated blood to the remaining physiological systems . CardiotMetformin (MET) is a biguanide-class drug used to treat diabetes, and its chemical name is N, N-dimethylimidodicarbonimidic diamide . InhibitRecent studies reported that MET can improve neurotoxicity and brain damage caused by chemotherapeutic agents such as cyclophosphamide and cisplatin in rodents ,48. In aConsequently, the primary objective of this study is to examine the impact of CMF treatment on thyroid hormone levels and ascertain the potential mitigating effect of MET co-treatment in alleviating the deleterious consequences of CMF treatment.The survival rate was unaffected by either saline or MET treatment. It is true that CMF treatment reduced rat survival by 40%; however, we observed a higher mortality rate in rats that were given both CMF and MET . After tThe findings indicate that both the saline and MET groups exhibited a gradual increase in body weight. Nevertheless, it is noteworthy that a statistical decrease in body weight was observed in the group of rats administered with CMF and the group of rats administered with CMF + MET, when related to the group of rats receiving saline a,b.The results of the electrochemiluminescence immunoassays (ECL) revealed no statistically significant differences in the concentrations of thyroid-stimulating hormone (TSH) among the experimental groups, namely the saline, CMF, MET, and CMF + MET groups. Nevertheless, a marginal elevation in the CMF and CMF + MET cohorts exhibited potential alterations in the thyroid-stimulating hormone (TSH) levels. Consequently, both the CMF and MET therapies exhibited negligible efficacy .According to the findings of the ECL analysis, the levels of T4 and FT4 in the group that had been treated with CMF had a significantly reduced concentration when compared with the rats that had been given saline. The T4 and FT4 levels did not improve despite the use of co-treatment with MET a,b.The ECL analysis exhibited that the levels of T3 and FT3 were notably lower in concentration in the CMF group in comparison with the saline rats; however, the MET therapy on its own did not appear to have a significant impact on the T3 or FT3 levels in comparison with the saline group. The combination of MET and CMF did not appear to have any effect a,b.The findings indicate that the MET group exhibited no changes in the troponin I, CK, and CK-MB levels related to the saline group. However, the CMF- and CMF + MET-treated rat groups revealed a significant increase in troponin I, CK, and CK-MB levels related to the saline group a–c.In the present investigation, we conducted an assessment to determine the influence of CMF intervention on the physiological functions of the thyroid and cardiac systems in rat models. This was achieved by evaluating the concentrations of thyroid-stimulating hormone (TSH), thyroxine (T4), free-thyroxine (FT4), triiodothyronine (T3), and free-triiodothyronine (FT3) in addition to troponin I, CK, and CK-MB levels in plasma samples. Furthermore, this study postulated that the concurrent administration of MET and CMF may potentially confer a safeguarding effect against the deleterious impact of CMF on the thyroid gland and cardiac tissue. Nevertheless, the evidence presented thus far indicates that MET does not elicit any discernible modifications in thyroid or cardiac functions, whether independently or in the presence of hypothyroidism or cardiotoxicity in rats. Consequently, it can be inferred that MET does not possess any protective effects on the aforementioned physiological functions of the thyroid or heart.Furthermore, it is noteworthy to mention that the groups administered saline and MET in isolation did not exhibit any discernible impact on the overall survival rate during the entire duration of the study. Nevertheless, it is worth noting that within the group subjected to CMF treatment, there was an observed occurrence of mortality, leading to a notable decrease in the overall survival rate, which amounted to 40 percent upon the conclusion of the study’s duration. Furthermore, a heightened incidence of mortality was noted in rodents subjected to the concomitant administration of CMF and MET, with a duration of only 50 percent throughout the duration of the investigation. Therefore, the simultaneous administration of MET in conjunction with CMF has the potential to induce increased drug toxicity or elicit a synergistic response against cellular entities, ultimately leading to cellular demise. The aforementioned observation displays similarities to our previous findings, wherein the rodents exposed to CMF demonstrated significantly increased concentrations of glutamate and dopamine, accompanied by the occurrence of mitochondrial dysfunction and lipid peroxidation in the brains of both the CMF- and CMF + MET-treated group. These alterations ultimately result in neuronal impairments and subsequent demise ,51. MoreBased on the available clinical and experimental research evidence, it has been observed that chemotherapy has the potential to exert an influence on thyroid function ,53. HencThe primary aim of this research was to elucidate the pharmacological impacts of CMF, MET, and the combined administration of CMF with MET on the regulation of thyroid-stimulating hormone (TSH), thyroxine (T4), free thyroxine (FT4), triiodothyronine (T3), and free triiodothyronine (FT3) concentrations. The TSH levels were not found to have any notable changes following the administration of CMF or MET in any of the experimental groups, thus yielding an unexpected result. Rats subjected to CMF treatment displayed a notable reduction in T4, FT4, T3, and FT3 concentrations, while administration of MET alone did not elicit any observable changes in these variables. Similarly, no discernible changes were noted in the serum levels of T4, T3, FT4, or FT3 following the administration of MET co-treatment. Therefore, it has been noted that the utilization of MET has not exhibited effectiveness in reinstating individuals with hypothyroidism to the ideal levels of T4, T3, FT4, or FT3. Additional research is required to evaluate different dosages and durations of MET with the aim of mitigating the deleterious effects of CMF-induced hypothyroidism.The previous literature has extensively reported that the administration of cyclophosphamide and fluorouracil can induce cardiotoxic effects, as indicated by the observed increase in troponin I and CK-MB concentrations ,57,58. TThe current investigation possesses certain limitations attributable to its in vivo characteristics. Further in vitro investigations and subsequent clinical trials are warranted to validate and substantiate the findings. Moreover, our research was regrettably unable to delve into the intricate mechanisms underlying the impacts of CMF and MET on the intricate workings of thyroid and cardiac functions. The investigation of the potential impact of CMF on thyroid and cardiac functions, specifically on the thyroid gland and the heart tissues, holds considerable intrigue.The research was performed at Qassim University’s College of Pharmacy in the Kingdom of Saudi Arabia between 1 and 30 July 2021.Cyclophosphamide (CYP) was procured from Baxter , Methotrexate (MTX) was acquired from Hospira UK Ltd. , Fluorouracil (5-FU) was sourced from Korea Company , and Metformin hydrochloride (MET) was gained from Tabuk Pharma Company .The animal house at Qassim University’s College of Pharmacy provided forty albino male rats weighing between 230 and 280 g for this study. The rodents spent their days in cages with a light-dark cycle of 12 h and a temperature of 25 ± 2 °C. The availability of food and water was never limited for them. The rodents were separated into four cohorts comprising ten rats each, wherein one cohort was designated as the control group receiving saline, another cohort received MET, the third cohort received CMF, and the fourth cohort received CMF + MET. Metformin (MET) was administered in the form of an aqueous solution, which was prepared by dissolving it in drinking water. The concentration of the solution was maintained at 2.5 mg per milliliter throughout the administration period . The CMF2). Blood specimens were expeditiously obtained and placed into tubes containing ethylenediaminetetraacetic acid (EDTA) from both the control group and the groups receiving treatment with MET, CMF, and CMF + MET. Subsequently, the vials containing the blood samples were subjected to centrifugation at a force of 12,000 times the acceleration due to gravity  for a duration of 10 min. The plasma, which underwent separation, was subsequently transferred to vials with a volume of 2 mL and stored at a temperature of −80 °C. Following the collection of blood samples, a comprehensive analysis was conducted employing a state-of-the-art fully automated analyzer. This sophisticated instrument employs a proprietary electrochemiluminescence technology to perform immunoassay analysis on various thyroid-related hormones, including TSH, T4, T3, FT4, and FT3, and cardiotoxicity biomarkers including troponin I, CK, and CM-MB. The ECL methodology was implemented utilizing the COBAS INTEGRA 400 plus system in strict accordance with the guidelines provided by the manufacturer, Roche Diagnostics, Germany.On the 14th day, subsequent to the final administration of the drug, the rats were humanely euthanized through cervical decapitation following the induction of anesthesia using carbon dioxide  were subjected to unidirectional analysis of variance (ANOVA), and the results were presented as the mean, standard error, as calculated using the GraphPad Prism 10.0.0.153 software . The data were subjected to the Dunnett multiple comparison test to evaluate the endpoints against the control, and The present investigation assessed the toxicological impact of CMF and explored the potential safeguarding effect of MET by employing rat models. The findings of this study offer substantiation indicating that CMF therapy may exert potential toxicological implications, as evidenced by an elevated mortality rate and a decrease in body weight. Additionally, it is plausible that this may result in the manifestation of hypothyroidism by means of diminishing levels of T4, FT4, T3, and FT3, without affecting TSH levels. Moreover, the results additionally revealed the potential occurrence of cardiotoxicity by means of heightened levels of troponin I, CK, and CK-MB. Regrettably, the aforementioned findings also suggest that MET does not bestow any protective properties against the toxic manifestations of hypothyroidism and cardiotoxicity induced by CMF in rat models.


The WHO AWaRe  antibiotic book which complements the WHO Model list of essential medicines and WHO Model list of essential medicines for children. The book gives specific guidance on the empiric use of antibiotics in the model lists with a strong emphasis on the AWaRe framework, which is centred around the risk of antimicrobial resistance development associated with the use of different antibiotics. Recommendations in the book cover 34 common infections in primary and hospital care both for children and adults. The book also includes a section on the use of the last-resort Reserve antibiotics, whose use should be restricted to very selected cases when an infection is confirmed or suspected to be caused by multidrug-resistant pathogens. The book highlights the use of first-line Access antibiotics or no antibiotic care if this is the safest approach for the patient. Here we present the background behind the development of the AWaRe book and the evidence behind its recommendations. We also outline how the book could be used in different settings to help reach the WHO target of increasing the proportion of global consumption of Access antibiotics to at least 60% of total consumption. The guidance in the book will also more broadly contribute to improving universal health coverage.Guidance on the appropriate use of antibiotics for common infections is lacking in many settings. The World Health Organization (WHO) has recently released  Global action plan on antimicrobial resistance.Optimizing the use of antibiotics is a key objective of the WHO WHO Model prescribing information: drugs used in bacterial infections,WHO AWaRe  antibiotic book,WHO Model list of essential medicines, WHO Model list of essential medicines for children and WHO’s AWaRe classification of antibiotics.–,In 2001, WHO published the Box 1Access antibiotics are antibiotics with a narrow spectrum of activity, generally with less side-effects, a lower potential for the selection of antimicrobial resistance and of lower cost. They are recommended for the empiric treatment of most common infections and should be widely available.Watch antibiotics generally have a higher potential for the selection of antimicrobial resistance and are more commonly used in sicker patients in the hospital facility setting. Their use should be carefully monitored to avoid overuse.Reserve antibiotics are last-resort antibiotics that should only be used to treat severe infections caused by multidrug-resistant pathogens.,WHO Model list of essential medicines and 36 antibiotics in the WHO Model list of essential medicines for children).–,WHO and others are increasingly employing the AWaRe classification to monitor antibiotic use and support antimicrobial stewardship activities.Box 2Amikacin; amoxicillin; amoxicillin + clavulanic acid; ampicillin; benzathine benzylpenicillin; benzylpenicillin; cefalexin; cefazolin; chloramphenicol; clindamycin; cloxacillin; doxycycline; gentamicin; metronidazole; nitrofurantoin; phenoxymethylpenicillin; procaine benzylpenicillin; spectinomycin (not listed in the model list for children); sulfamethoxazole + trimethoprim; and trimethoprim.Azithromycin; cefixime; cefotaxime; ceftazidime; ceftriaxone; cefuroxime; ciprofloxacin; clarithromycin; meropenem; piperacillin + tazobactam; and vancomycin.Cefiderocol (not listed in the model list for children); ceftazidime + avibactam; colistin; fosfomycin; linezolid; meropenem + vaborbactam (not listed in the model list for children); plazomicin (not listed in the model list for children); and polymyxin B.Staphylococcus aureus ; glycopeptides exposure increased the risk for vancomycin-resistant Enterococcus ; and carbapenems exposure increased the risk for carbapenem-resistant Acinetobacter baumannii , carbapenem-resistant Enterobacterales  and carbapenem-resistant Pseudomonas aeruginosa . These findings support the principles of The WHO AWaRe  antibiotic book, which is to increase the proportion of patients treated with Access antibiotics or no antibiotic treatment where appropriate.In a meta-analysis, researchers assessed the risk of colonization or infection by multidrug-resistant pathogens after exposure to antibiotics classified by the AWaRe categories.,Salmonella spp. blood culture isolates,The book was developed by the Essential Medicines List Secretariat with the support of the Essential Medicines List Antimicrobial Working Group. The book builds around the recommendations of using specific antibiotics for specific infections given in the 2017 model lists. The development of these recommendations for specific antibiotics for the treatment of common acute infections followed an evidence-based and open process that included assessments of more than 1000 clinical trials, systematic reviews and international clinical practice guidelines . To ensuBox 32015:Global action plan on antimicrobial resistance adopted by the World Health Assembly2016: WHO Model list of essential medicines and WHO Model list of essential medicines for childrenThe Essential Medicine List Secretariat established an Essential Medicine List Antimicrobial Working Group composed of global experts to update the list of antibiotics in the The working group evaluated the evidence from systematic reviews and meta-analyses of randomized controlled trials of antibiotic treatment for all relevant infections and international clinical practice guidelinesThe working group delegated the task of reviewing the evidence to the Centre for Infectious Diseases, Research Methods and Recommendations of McMaster University, Hamilton, CanadaThe Essential Medicine List Expert Committee reviewed the antibiotics proposed by the working group and made the final recommendations on antibiotics for inclusion in both model lists2017: AWaRe framework introduced Update of both model lists: a major revision of antibiotics in the list is conducted following the comprehensive evaluation of systematic reviews and meta-analyses of randomized controlled trials and clinical practice guidelines for the treatment of common infections2019: AWaRe revised . Introduction of a “not recommended” categoryUpdate of both model lists: antibiotic treatment for two additional infections  and surgical prophylaxis were reviewed2021:AWaRe revisedUpdate of both model lists: antibiotic treatment for two additional infections was reviewed The book includes individual chapters for 34 common clinical infections in children and adults in both the primary health care and hospital settings. Each chapter provides information regarding the clinical management of the infection, common clinical presentation (of mild and severe cases) and key diagnostic tests to consider. Each chapter is focused on antibiotic treatment strategies at the time of first clinical presentation , when a working clinical diagnosis has been made based on the patient’s history and examination, but test results are not yet available .Box 4Bronchitis: no antibioticAcute otitis media: amoxicillin (A)Pharyngitis: phenoxymethylpenicillin (A) or amoxicillin (A)Acute sinusitis: amoxicillin (A) or amoxicillin + clavulanic acid (A)Dental infections: amoxicillin (A) or phenoxymethylpenicillin (A)Acute localized lymphadenitis: amoxicillin + clavulanic acid (A) or cefalexin (A) or cloxacillin (A)Mild community-acquired pneumonia: amoxicillin (A) or phenoxymethylpenicillin (A)COPD exacerbations: amoxicillin (A)Infectious bloody diarrhoea or dysentery: ciprofloxacin (W)Enteric fever: ciprofloxacin (W) or azithromycin or ceftriaxone (W)Skin and soft tissue infections : amoxicillin + clavulanic acid (A) or cefalexin (A) or cloxacillin (A)Burn and wound-related infections: amoxicillin + clavulanic acid (A) or cefalexin (A) or cloxacillin (A)Lower urinary tract infections: nitrofurantoin (A) or sulfamethoxazole + trimethoprim (A) or trimethoprim (A) or amoxicillin + clavulanic acid (A)COPD: chronic obstructive pulmonary disease.Note: (A) denotes Access antibiotics and (W) denotes Watch antibiotics.Box 5Sepsis (adults): ceftriaxone (W) or cefotaxime (W) combined with gentamicin (A) or amikacin (A)Sepsis (neonates or children): ampicillin (A) or benzylpenicillin (A) combined with gentamicin (A)Bacterial meningitis (adults or children): ceftriaxone (W) or cefotaxime (W)Bacterial meningitis (neonates): ampicillin (A) combined with gentamicin (A) Severe community-acquired pneumonia: ceftriaxone (A) or cefotaxime (A) combined with clarithromycin (A)Community-acquired pneumonia (children): ampicillin (A) or amoxicillin (A) or benzylpenicillin (A) combined with gentamicin (A)Hospital-acquired pneumonia: amoxicillin + clavulanic acid (A) or ceftriaxone (W) or cefotaxime (W) or piperacillin + tazobactam (W)Mild intra-abdominal infectiona: amoxicillin + clavulanic acid (A) or ceftriaxone (W) or cefotaxime (W) combined with metronidazole (A)Severe intra-abdominal infectiona: piperacillin + tazobactam (W) or ceftriaxone (W) or cefotaxime (W) combined with metronidazole (A)Mild upper urinary tract infection: ciprofloxacin (W)Severe upper urinary tract infection: ceftriaxone (W) or cefotaxime (W) combined with gentamicin (A) or amikacin (A)Bone and joint infectionb: cloxacillin (A)Severe skin and soft tissue infections (necrotizing fasciitis): piperacillin + tazobactam (W) combined with clindamycin (A) or ceftriaxone (W) combined with metronidazole (A)Severe skin and soft tissue infections (pyomyositis): amoxicillin + clavulanic acid (A) or cefalexin (A) or cloxacillin (A)Febrile neutropenia (with low risk of serious infection): amoxicillin + clavulanic acid (A) combined with ciprofloxacin (W)Febrile neutropenia (with high risk of serious infection): piperacillin + tazobactam (W)Surgical prophylaxisc: cefazolin (A) or cefazolin (A) combined with metronidazole (A)a Appendicitis, cholangitis/cholecystitis, diverticulitis, pyogenic liver abscess.b Septic arthritis and osteomyelitis.c The choice of prophylaxis depends on the type of surgical procedure.Note: (A) denotes Access antibiotics and (W) denotes Watch antibiotics.Clinical signs and symptoms to assess the risk of more complicated courses  are summarized in each infection chapter.All chapters are complemented by infographics summarizing the key information for each infection in a user-friendly, quickly accessible format. A mobile application of the book contents, and the book in e-pub format are also freely available and can be used both on- and offline.A key aim of the book is to highlight low-risk cases of certain infections where the preferred approach is to observe and wait, providing symptomatic treatment but no antibiotics, based on the initial clinical risk assessment for severity and complications. For example, mild infections, often likely to be of viral origin, in otherwise healthy individuals, could be treated in such a way to avoid the unnecessary use of antibiotics. Box 6a because the infection is of viral origin and the illness is usually self-limiting regardless of the causative pathogen. The cornerstone of treatment is rehydration.Most cases do not require antibiotic treatmentNearly all cases have a viral origin and there is no evidence that antibiotics are needed.Most exacerbations are not triggered by bacterial infections; only certain cases will benefit from antibiotic treatment.Dental treatment rather than prescribing antibiotics is generally more appropriate in the management of dental infections.Most non-severe cases can be managed symptomatically and do not require antibiotic treatment.Most cases do not require antibiotics because the infection is commonly viral.Most cases do not require antibiotics because the infection is commonly viral.In cases of wounds at low risk of becoming infected, antibiotic treatment is not needed.In cases of animal bites, only wounds in high-risk anatomical locations and patients with severe immunosuppression benefit from antibiotic treatment.In young women who are not pregnant, with mild symptoms and who may wish to avoid or delay antibiotic treatment, symptomatic treatment alone can be considered.COPD: chronic obstructive pulmonary disease.a Unless significant bloody diarrhoea is present.b Symptomatic care as first line treatment for lower urinary tract infections only applies to a few selected patients with no risk factors for complicated infections.The book gives appropriate information on dosing and treatment duration with an emphasis on encouraging treatment for the shortest acceptable duration. An early switch from intravenous to oral treatment is strongly encouraged to enable clinically appropriate hospital discharge as soon as possible. The section on dose and duration is aligned with guidance developed by the United Kingdom National Institute for Health and Care Excellence, which is based on extensive evidence-based reviews of the literature.WHO Model list of essential medicines based on their public health utility. For each of these last-resort antibiotics, guidance is provided on where their targeted and empiric use might be considered appropriate, along with practical prescribing information. The guidance fully acknowledges that local factors, such as availability of microbiology laboratories, need to be considered, and avoidance of inappropriate use of these antibiotics must be a priority.Reserve antibiotics are selected for the While updating the WHO guidance on optimal antibiotic use for common infections took 20 years, it is important that antibiotic recommendations in the book are updated regularly. Updating a single globally relevant guidance that covers dozens of diseases and multiple treatment options is challenging. The use of the WHO Global Antimicrobial Resistance and Use Surveillance System, along with closer linkages between people updating the model lists and other WHO antimicrobial resistance stewardship programmes and policy initiatives will facilitate the process. While comprehensive antibiotic guidance is a crucial component of any antimicrobial resistance stewardship programme, it has a limited impact as an isolated intervention.From simply listing antibiotics in the adult and children model lists to providing detailed guidance on their optimal use in the book is a major step in ensuring equity of access. Policy-makers can use the information provided in the book to set policies that help in achieving several targets. Target 3.8 of the sustainable development goals identifies access to safe, effective, quality and affordable medicines for all as a key component of achieving universal health coverage (UHC). The clear and specific guidance in the book on the appropriate use of narrow- and broad-spectrum antibiotics listed in WHO’s model lists is an important step towards achieving UHC while at the same time preserving the antibiotics’ continued efficacy. By using the book, policy-makers can determine equity of access to effective antibiotics for specific clinical conditions in both the primary care and hospital setting. They will be able to determine not only if the medicine is available generally in the health-care facility, but also if it is available to treat a patient with a specific infection, at the right dose and duration, in a safe, effective, quality-assured and affordable formulation. With the target of at least 60% Access antibiotics in place, the book will support achieving the target by clarifying how detailed, timely, reliable and actionable data could now be derived on access to the essential AWaRe antibiotics. Using this approach to treat common infections would be an important step towards combatting antimicrobial resistance and creating healthier populations.