Microparticles of rifampicin: comparison of pulmonary route with oral route for drug uptake by alveolar macrophages, phagocytosis activity and toxicity study in albino rats

Context: Tuberculosis (TB) is a chronic infectious disease with increasing incidence of drug resistance. Oral treatment for TB and multidrug resistance (MDR)-TB can have serious side effects. The causative agent of TB, Mycobacterium tuberculosis, resides in alveolar macrophages (AM). Pulmonary administration of anti-TB drugs can help in delivery of high concentration to AM. The ability of AM to phagocytose can also be utilized to generate mycobactericidal nitric oxide (NO) to improve efficacy of anti-TB drugs. Objective: To compare the uptake of rifampicin (RIF) by AM post oral and pulmonary administration of RIF microparticles (RM) and to compare hepatotoxicity and phagocytosis activity. Materials and Methods: RM were produced by spray drying process. RM were administered to rats through oral as well as intratracheal route. The uptake of RIF by AM and liver was measured. NO was measured in bronchoalveolar lavage (BAL) fluid. SGOT and SGPT levels were measured in serum. Results: Significantly higher (p < 0.05) concentration of RIF was found in AM post intratracheal administration. NO production was also significantly higher but less than toxic level. SGOT and SGPT levels as well as uptake of RIF by liver were indicative of no hepatotoxicity post intratracheal administration. Discussion: Phagocytosis of RM post intratracheal administration leads to significantly higher drug level in AM as well as production of significantly higher levels of NO. Conclusion: The administration of RM as dry powder inhalation (DPI) formulation may reduce treatment time of TB and chances of drug resistance TB.