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 sustained levels of drug release for prolonged periods. These levels are comparable to those attained following daily oral administration of the drug. We have shown that by such administration, high in vivo chemotherapeutic activity, similar to that achieved by daily oral administration, was seen. Parallel to these studies we assessed the release pattern of the drug from the polymer in vitro, in simulated in vivo conditions and in experimental animals, using chemical methods for drug analysis and polarization, scanning and transmission electron microscopy techniques for implant characterization. These investigations have shown sustained release of isoniazid from a PLGA matrix in aqueous medium under several storage conditions. Polarization microscopy has verified the stability of the drug for the prolonged periods of release. Scanning electron microscopy has been helpful in observing the three-dimensional structural changes that occur in the polymer/drug matrix that occur during the in vivo drug release.