Dissolution-Controlled Nanocrystalline Rifapentine Formulation for Tuberculosis Treatment

Current tuberculosis (TB) treatment suffers from drawbacks such as long regimens, high pill burden and side effects leading to non-adherence and poor treatment outcomes. Dissolution-controlled drug depot formulation with high drug loading is a clinically successful drug delivery strategy. Such depots reduce the dosing frequency for treatments requiring daily administration, thereby improving treatment adherence and compliance. However, dissolution-controlled depots for first-line TB drugs have not been demonstrated due to their high solubility and high dose requirements. In this study, we overcame this challenge by developing injectable, extended-release, dissolution-controlled depots of nanocrystalline rifapentine (NCRPT), microcrystalline rifapentine (MCRPT) and amorphous rifapentine microparticles (ARPT) with more than 75% loading. Crystalline formulations resulted in much slower depot dissolution compared to amorphous formulations. A single intramuscular (IM) injection of NCRPT in mice resulted in therapeutic serum concentrations for over a week. We then demonstrated the efficacy of NCRPT in both pre-exposure prophylaxis and therapeutic models of mice TB. NCRPT administered at 60 mg/kg once every two weeks demonstrated excellent efficacy in a mouse model of TB infection. In each case, a ∼ 4-log-fold reduction in lung bacterial load compared to untreated mice was observed. These results open new avenues for developing LAI formulations of TB drugs and could improve patient compliance and TB management.