In situ gelling drug delivery systems for periodontal anaesthesia.
In this thesis local anaesthetic formulations based on PEO-PPO-PEO block copolymers (PEO and PPO being poly(ethylene oxide) and poly(propylene oxide), respectively) or nonionic cellulose ethers undergoing temperature- or dilution-induced thickening were investigated. The aim of the work was to develop formulations which can be easily administered to the periodontal pocket, stay at the application site, give a fast onset of anaesthesia and have a duration sufficient to perform periodontal scaling procedures. Emulsions, (mixed) micellar solutions and microemulsions fulfilling the requirements stated above were achieved by combining the active ingredients lidocaine and prilocaine with the nonionic block copolymers Lutrol® F127 and Lutrol® F68. The critical micellisation and gelation temperatures of the systems were found to be interconnected and influenced by the total polymer concentration and the polymer mixture composition, as well as the presence of cosolutes and pH. A low-viscous isotropic phase that turns into a high-viscous hexagonal phase as the water content increases was found by combining Lutrol® F68, water, a eutectic mixture of lidocaine and prilocaine and Akoline MCM. The system has a slower release rate compared to the microemulsion formulation which might make it suitable for indications where a longer duration is needed. Finally, a temperature-induced gelling system was achieved by adding lidocaine and prilocaine to mixtures of ethyl(hydroxyethyl)cellulose (EHEC) and sodium dodecyl sulfate (SDS), hexadecyltrimethylammonium bromide (CTAB) or myristoylcholine bromide systems at, or just below, the surfactant concentration found to give a maximum viscosity increase at room temperature. In particular, the myristoylcholine bromide system may be interesting considering its antibacterial properties and biodegradability.
Evaluation of polaxomer-based in situ gelling system of articaine as a drug delivery system for anesthetizing periodontal pockets – An in vitro study
Abstract Background Articaine hydrochloride, a water soluble local anesthetic, is administered by block/infiltration anesthesia during the treatment of periodontitis. The pain, associated with injection of local anesthetics, can be overcome by the use of in situ gel forming system of local anesthetics. The system is a low viscosity fluid at room temperature and rigid elastic gel at body temperature, undergoing in situ sol–gel transition. Methods The present work describes the formulation, characterization and preliminary drug release studies of muco-adhesive formulations containing articaine, polaxomer 407 as the thermoreversible gelling agent in combination with hydroxypropylmethylcellulose (HPMC) and Carbopol 934P, as a muco-adhesive agent. Each formulation was characterized in terms of gelling temperature, viscosity, muco-adhesive force, spreadability, drug release. Results The gelling temperature varied with the polymer concentration and the presence of drug. Increasing concentrations of each polymeric component also increased the viscosity and muco-adhesion of the formulations. The in vitro and ex vitro permeation studies indicated the sustained drug release for a 7-h period. The release study suggested zero-order kinetics and gel erosion and diffusion as possible mechanisms of drug release. Conclusion The developed system is a viable alternative for the conventional injectable dosage form.
Computer-Aided System of Virtual Testing of Gas Turbine Engines
The article describes the concept of a virtual lab that includes subsystem of gas turbine engine simulation, subsystem of experiment planning, subsystem of measurement errors simulation, subsystem of simulator identification and others. The basis for virtual lab development is the computer-aided system of thermogasdynamic research and analysis “ASTRA”. The features of gas turbine engine transient modes simulator are described. The principal difference between the simulators of transient and stationary modes of gas turbine engines is that the energy balance of the compressor and turbine becomes not applicable. The computer-aided system of virtual gas turbine engine testing was created using the developed transient modes simulator. This system solves the tasks of operational (throttling, speed, climatic, altitude) characteristics calculation, analysis of transient dynamics and selection of optimal control laws. Besides, the system of virtual gas turbine engine testing is a clear demonstration of gas turbine engine working process and the regularities of engine elements collaboration. The interface of the system of virtual gas turbine engine testing is described in the article and some screenshots of the interface elements are provided. The developed system of virtual gas turbine engine testing provides means for reducing the laboriousness of gas turbine engines testing. Besides, the implementation of this system in the learning process allows the diversification of lab works and therefore improve the quality of training.