Antibiotic release from biodegradable PHBV microparticles

For the treatment of periodontal diseases, design of a controlled release s ystem seemed very appropriate for an effective, long term result. In this s tudy a novel, biodegradable microbial polyester, poly(3-hydroxybutyrate-co- 3-hydroxyvalerate), PHBV of various valerate contents containing a well est ablished antibiotic, tetracycline, known to be effective against many of th e periodontal disease related microorganisms, was used in the construction of a controlled release system. Tetracycline was loaded in the PHBV microsp heres and microcapsules both in its acidic (TC) and in neutral form (TCN). Microcapsules of PHBV were prepared under different conditions using w/o/w double emulsion and their properties such as encapsulation efficiency, load ing, release characteristics, and morphological properties were investigate d. It was found that concentration of emulsifiers polyvinyl alcohol (PVA) a nd gelatin (varied between 0-4%) influenced the encapsulation efficiency ap preciably. In order to increase encapsulation efficiency (from the obtained range of 18.1-30.1%) and slow down the release of the highly soluble tetra cycline. HCl, it was neutralized with NaOH. Encapsulation efficiency of neu tralized tetracycline was much higher (51.9-65.3%) due to the insoluble for m of the drug used during encapsulation. The release behaviour of neither o f the drugs was found to be of zero order. Rather the trends fitted reasona bly well to Higuchi's approach for release from spherical micropheres. Biod egradability was not an appreciable parameter in the release from microcaps ules because release was complete before any signs of degradation were obse rved. (C) 1999 Elsevier Science B.V. All rights reserved.