Alternative Pharmaceutical Formulation for Oral Administration of Rifampicin

Tuberculosis (TB) is considered an emergency global public health, mainly due to the TB-HIV co-infection, bacillus dormancy stage, and emergence of resistant strains. In addition, the therapeutic toxicity and its pharmacokinetic interactions with other drugs may influence treatment non-compliance, low serum concentration of drugs, and, consequently, treatment failure. Strategies using nanotechnology represent a new tool for the therapy, since they are effective delivery systems due to the possibility of solubilization of hydrophobic compounds, enable the production of formulations for oral use, and, in addition, increase bioavailability of drugs. This study aimed to develop a nanoemulsion (NE) containing rifampicin (RIF-NE) and evaluate its in vitro antimycobacterial activity using Resazurin Microtiter Assay against three Mycobacterium tuberculosis strains: two susceptible and a multidrug-resistant. Using the hot solvent diffusion method associated with phase inversion technique was possible to develop a liquid formulation containing 500 μg/mL rifampicin (RIF), which is a hydrophobic compound, of average size 25 nm. The results showed that the minimum inhibitory concentration of the encapsulated RIF was equal to the free form of RIF, indicating that the process of production of NEs did not affect the activity of the compound. Thus, RIF-NE could be a promising alternative for oral administration of RIF, being considered a child-friendly pharmaceutical formulation. Its application could avoid the administration of unknown and/or non-ideal concentrations, being functional in the regimes of prevention and treatment of TB and, in addition, in the fight against drug resistance.