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.
An Overview of In Situ Gel Forming Implants: Current Approach Towards Alternative Drug Delivery System
Usually, researchers find the difficulties for the development of novel drug delivery systems by implementing the novel technologies. Also there are lots of challenges to make these systems site specific for effective drug delivery for extended period of time. A novel biodegradable, injectable polymeric system namely in-situ forming implants (ISFIs) looks very promising drug delivery system. In-situ gel formation of drug delivery systems can be defined as a liquid formulation generating a solid or semisolid depot after administration. It is a blend of drug and biodegradable polymers dissolved or suspended in pharmaceutically acceptable water-miscible organic solvents. These are generally liquid formulations that form semi-solid or solid depots after injection at the injection site due to phase separation and provide a prolonged release over weeks to few months duration. After subcutaneous injection of ISFI the organic solvent dissipates into the surrounding tissue as water penetrates in, this leads to phase separation and precipitation of the polymer forming a depot (gel) at the injection site. The drug entrapped in the depot is then slowly released out into the surrounding body fluid due to the degradation of the polymers and finally reaches the systemic circulation. These high-value formulations ensure patient compliance; will contribute in the design and development of biotechnologically based products. The present review mainly focuses on advantages, disadvantages, classification, composition, methods and evaluation of in-situ gelling implants.
Tourism in the Amazon: identifying challenges and finding solutions
Purpose – The purpose of this paper is to provide an overview of the tourism sector in the Amazon regions of Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, and Suriname and then discuss the manner in which tourism activity assists the protection of the Amazon rainforests. The paper also describes the manner in which the first World Hospitality and Tourism Themes Roundtable on Tourism in the Amazon is organized in 2009.Design/methodology/approach – Teams of researchers from the Ministries of Tourism, the private sector and academia in the Member Countries of Treaty for Amazon Cooperation collaborated to address, in ten‐page papers, the question “Does sustainable tourism offer solutions for the protection of the Amazon rainforest?”Findings – The paper provides valuable information on the current state of tourism policy and practice in the Amazon Member Countries. It also articulates the challenges that attend the development of sustainable tourism as a mechanism for the protection of the Amazon.Practical...