RELEASE OF ISONIAZID FOR PROLONGED PERIODS FROM A BIODEGRADABLE POLYMER UNDER SEVERAL IN-VITRO AND SIMULATED IN-VIVO CONDITIONS AND IN ANIMALS

Earlier studies by us have shown that a single subcutaneous implant of isoniazid in polylactic co-glycolic acid (PLGA) polymer showed sustai ned levels of drug release for prolonged periods. These levels are com parable to those attained following daily oral administration of the d rug. We have shown that by such administration, high in vivo chemother apeutic activity, similar to that achieved by daily oral administratio n, was seen. Parallel to these studies we assessed the release pattern of the drug from the polymer in vitro, in simulated in vivo condition s and in experimental animals, using chemical methods for drug analysi s and polarization, scanning and transmission electron microscopy tech niques for implant characterization. These investigations have shown s ustained release of isoniazid from a PLGA matrix in aqueous medium und er several storage conditions. Polarization microscopy has verified th e stability of the drug for the prolonged periods of release. Scanning electron microscopy has been helpful in observing the three-dimension al structural changes that occur in the polymer/drug matrix that occur during the in vivo drug release.