Biodegradable polymers have played an important role in the delivery of drugs in a controlled and targeted manner. Polylactic-co-glycolic acid (PLGA) is one of the extensively researched synthetic biodegradable polymers due to its favorable properties. It is also known as a 'Smart Polymer' due to its stimuli sensitive behavior. A wide range of PLGA-based drug delivery systems have been reported for the treatment or diagnosis of various diseases and disorders. The present review provides an overview of the chemistry, physicochemical properties, biodegradation behavior, evaluation parameters and applications of PLGA in drug delivery. Different drug-polymer combinations developed into drug delivery or carrier systems are enumerated and discussed.

Abstract. Piroxicam is used in the treatment of rheumatoid arthritis, osteoarthritis, and other inflammatory diseases. Upon oral administration, it is reported to cause ulcerative colitis, gastrointestinal irritation, edema and peptic ulcer. Hence, an alternative delivery system has been designed in the form of transethosome. The present study describes the preparation, optimization, characterization, and ex vivo study of piroxicam-loaded transethosomal gel using the central composite design. On the basis of the prescreening study, the concentration of lipids and ethanol was kept in the range of 2-4% w/v and 0-40% v/v, respectively. Formulation was optimized by measuring drug retention in the skin, drug permeation, entrapment efficiency, and vesicle size. Optimized formulation was incorporated in hydrogel and compared with other analogous vesicular (liposomes, ethosomes, and transfersomes) gels for the aforementioned responses. Among the various lipids used, soya phosphatidylcholine (SPL 70) and ethanol in various percentages were found to affect drug retention in the skin, drug permeation, vesicle size, and entrapment efficiency. The optimized batch of transethosome has shown 392.730 μg cm −2 drug retention in the skin, 44.312 μg cm −2 h −1 drug permeation, 68.434% entrapment efficiency, and 655.369 nm vesicle size, respectively. It was observed that the developed transethosomes were found superior in all the responses as compared to other vesicular formulations with improved stability and highest elasticity. Similar observations were noted with its gel formulation.

Capsaicin, extracted from the fruits of Capsicum, is a powerful local stimulant with strong rubifacient action, devoid of vesication. Topical use of capsaicin is quite common in the treatment of various pain-associated musculo-skeletal disorders, itching and neuropathy. Despite its high pharmacodynamic potential, the patient compliance to the drug is reported to be poor owing to multiple skin problems like irritation, burning sensation, and erythma. The present study targets the encasement of drug in the interiors of flexible membrane vesicles (FMVs), as these are reported to have better penetration in the deeper layers of skin, thus leading to enhanced localization of drug and consequently, decreased skin irritation. Multilamellar drug-loaded FMVs, prepared by thin-film hydration were evaluated for their efficacy in vitro and in vivo. When compared with conventional liposomes, the formulated FMVs showed higher skin retention during ex vivo permeation studies employing LACA mice skin, higher analgesic potential using radiant tail-flick method in mice, and better flexibility in regaining their size. Being less of an irritant, these vesicular carriers were also found to be more comfortable on human skin. Thus, the capsaicin-loaded FMVs offer high potential as topical drug delivery technologies with improved patient acceptance and effectiveness.

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Nimesulide, a non-steroidal anti-inflammatory drug, was incorporated into multilamellar liposomes to improve its performance on topical administration. The drug was loaded onto liposomes employing thin film hydration technique. Various process and formulation variables were investigated to obtain the liposomal products of desired quality. Liposomes were monitored for percent drug entrapment, after separating the unentrapped drug by mini column centrifugation, for vesicular properties (such as size distribution profile, morphological attributes and agglomeration tendency), drug diffused through synthetic semipermeable membrane, and drug leakage. Systematic optimization studies were carried out using 3(2) factorial design to select the optimized liposomal composition with reference to percent drug entrapment, drug diffusion and leakage. The optimized batch of liposomes was subjected to drug permeation and drug retention studies employing rat skin and human cadaver skin. In comparison to methanolic solution of pure nimesulide, liposomal formulations were found to retain higher amounts of nimesulide in the skin. Anti-inflammatory studies, using carragenan-induced rat paw edema model, indicated significantly better performance of liposomally entrapped nimesulide in comparison to the marketed gel formulation and the Carbopol gel containing nimesulide.