International Journal of Pharma Research and Development – Online 01/2011; 3:March/012.

ABSTRACT Recent drug discovery using advanced techniques such as genomics, combinatorial chemistry, high
throughput screening and in silico three dimensional drug design has yielded drug candidates with low
water solubility and thus an inherently low mucosal permeability which makes the development of
pharmaceutical formulations difficult. To overcome these, particulate systems like microparticles have
been used as a physical approach to alter and improve the pharmacokinetic and pharmacodynamics
properties of various types of drug molecules. They have been used in vivo to protect the drug entity in
the systemic circulation, restrict access of the drug to the chosen sites and to deliver the drug at a
controlled and sustained rate to the site of action. Various polymers have been used in the formulation
of microparticles for drug delivery research to increase therapeutic benefit, while minimizing side
effects. The review embraces various aspects of microparticle formulations, characterization, effect of
their characteristics and their applications in delivery of drug molecules and therapeutic genes.

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    ABSTRACT: Although numerous protein therapeutics have been approved or are in advanced clinical testing, the development of more sophisticated delivery systems for this rapidly expanding class of therapeutic agents has not kept pace. The short in vivo half-lives, the physical and chemical instability, and the low oral bioavailability of proteins currently necessitate their administration by frequent injections of protein solutions. This problem can be overcome by use of injectable depot formulations in which the protein is encapsulated in, and released slowly from, microspheres made of biodegradable polymers. Although the first report of sustained release of a microencapsulated protein was more than 20 years ago, the instability of proteins in these dosage forms has prevented their clinical use. Advances in protein stabilization, however, have allowed development of sustained-release forms of several therapeutic proteins, and clinical testing of a monthly formulation human growth hormone is currently in progress. The obvious advantage of this method of delivery is that the protein is administered less frequently, sometimes at lower overall doses, than when formulated as a solution. More importantly, it can justify commercial development of proteins that, for a variety of reasons, could not be marketed as solution formulations.
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    ABSTRACT: A considerable research has been conducted on drug delivery by biodegradable polymeric devices, following the entry of bioresorbable surgical sutures in the market about two decades ago. Amongst the different classes of biodegradable polymers, the thermoplastic aliphatic poly(esters) like poly(lactide) (PLA), poly(glycolide) (PGA), and especially the copolymer of lactide and glycolide, poly(lactide-co-glycolide) (PLGA) have generated immense interest due to their favorable properties such as good biocompatibility, biodegradability, and mechanical strength. Also, they are easy to formulate into different devices for carrying a variety of drug classes such as vaccines, peptides, proteins, and micromolecules. Also, they have been approved by the Food and Drug Administration (FDA) for drug delivery. This review discusses the various traditional and novel techniques (such as in situ microencapsulation) of preparing various drug loaded PLGA devices, with emphasis on preparing microparticles. Also, certain issues about other related biodegradable polyesters are discussed.
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    ABSTRACT: Poly(lactic acid) [PLA] and its co-polymers with glycolic acid [PLCG] have been known to be biodegradable and histocompatible for the past 20 years. Their physico-chemical and biological properties have been found suitable, in many instances, for sustaining drug release in vivo for days or months. Several dosage forms for parenteral administration have been investigated using these polymers and a microencapsulation technique is chosen frequently for its unique properties. There are a limited number of published papers concerning preparation and characterization of PLA or PLCG microcapsules, possibly because of commercial unavailability and difficulties in the synthesis of reproducible batches of these polymers. However, microcapsules can be made using different traditional and non-traditional techniques containing core materials ranging from biological proteins to synthetic drugs. An attempt is made here to review problems associated with the different microencapsulation techniques using PLA or PLCG. In vivo and in vitro drug release from these microcapsules is also reviewed.
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