Efficacy of rifabutin-loaded microspheres for treatment of Mycobacterium avium-infected macrophages and mice.

Two poly(DL-lactide-co-glycolide) microsphere formulations (A, 10% wt/wt, and B, 23% wt/wt, 1-10 microns) were evaluated for intracellular delivery of rifabutin using the J774 murine and Mono Mac 6 (MM6) human monocytic cell lines. Within 7 days, formulation A released 100% in both cell lines and B released 53 and 67% in the J774 and MM6, respectively. Intracellular release of rifabutin with both formulations caused significant reduction of intracellularly replicating Mycobacterium avium (MAC).

Sustained release characteristics of rifampin-loaded microsphere formulations in nonhuman primates.

Controlled release rifampin-loaded microspheres were evaluated for the first time in nonhuman primates. Animals received either 2.0 g of a large formulation (10-150 microm, 23 wt% rifampin) injected subcutaneously at Day 0 (118-139 mg rifampin/kg), 4.

The fate of biodegradable microspheres injected into rat brain.

Biodegradable microspheres made with poly-[D,L-lactide-co-glycolide] represent an evolving technology for drug delivery into the central nervous system. Even though these microspheres have been shown to be engulfed by astrocytes in vitro, the purpose of the present study was to track the fate of biodegradable microspheres in vivo. This was accomplished using microspheres containing the fluorescent dye coumarin-6 followed 1 day, 1 week and 1 month after intracerebral injections of this material were made into the rat brain.