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BioMed Research International
Volume 2013 (2013), Article ID 387863, 11 pages
http://dx.doi.org/10.1155/2013/387863
Research Article

Release of a Wound-Healing Agent from PLGA Microspheres in a Thermosensitive Gel

1US Army Dental and Trauma Research Detachment, Institute of Surgical Research, 3650 Chambers Pass, Building 3610, JBSA Fort Sam Houston, TX 78234-6315, USA
2Faculty of Pharmaceutical Sciences, University of Kentucky College of Pharmacy, Lexington, KY 40506, USA

Received 13 May 2013; Revised 15 August 2013; Accepted 16 August 2013

Academic Editor: Frederic Lagarce

Copyright © 2013 H. A. Machado et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The purpose of this research was to develop a topical microsphere delivery system in a thermosensitive 20% poloxamer 407 gel (Pluronic F127) to control release of KSL-W, a cationic antimicrobial decapeptide, for a period of 4–7 days for potential application in combat related injuries. KSL-W loaded microsphere formulations were prepared by a solvent extraction-evaporation method (water-oil-water), with poly (D,L-lactic-co-glycolic acid) (PLGA) (50 : 50, low-weight, and hydrophilic end) as the polymeric system. After optimization of the process, three formulations (A, B, and C) were prepared with different organic to water ratio of the primary emulsion while maintaining other components and manufacturing parameters constant. Formulations were characterized for surface morphology, porous nature, drug loading, in vitro drug release, and antimicrobial activity. Microspheres containing 20% peptide with porous surfaces and internal structure were prepared in satisfactory yields and in sizes varying from 25 to 50 μm. Gels of 20% Pluronic F127, which were liquid at or below 24.6°C and formed transparent films at body temperature, were used as carriers for the microspheres. Rheological studies showed a gelation temperature of 24.6°C for the 20% Pluronic F127 gel alone. Gelation temperature and viscosity of formulations A, B, and C as a function of temperature were very close to those of the carrier. A Franz diffusion cell system was used to study the release of peptide from the microspheres suspended in both, phosphate-buffered saline (PBS) and a 20% Pluronic F127 gel. In vitro release of greater than 50% peptide was found in all formulations in both PBS and the gel, and in one formulation there was a release of 75% in both PBS and the gel. Fractions collected from the release process were also tested for bactericidal activity against Staphylococcus epidermidis using the broth microdilution method and found to provide effective antimicrobial activity to warrant consideration and testing in animal wound models for treating combat-related injuries.