Experimental chemotherapy of tuberculosis using single dose treatment with isoniazid in biodegradable polymers

In previous studies we showed that a single implant of polylactic-co-glycolic acid (PLGA) polymer as a film containing isoniazid ensured sustained release of the drug for up to 4 weeks. These studies have been extended to PLGA polymer as a rod which is retrievable. Both types of implant gave therapeutically active levels of free isoniazid in liver and urine for prolonged periods. We assessed the in vivo chemotherapeutic efficacy of the rod implant against heavy infections of virulent Mycobacterium tuberculosis in C57Bl/6 mice. The chemotherapeutic data essentially confirmed the bioavailability data. In one chemotherapeutic study, one (7%) out of 15 mice which received the isoniazid polymer implant died within 30 days of bacterial challenge, while none of those receiving daily oral treatment died. In contrast, 14 (93%) of the 15 control mice died during the same period. In a second study similar results were obtained.