Flurbiprofen restores rifampicin and isoniazid sensitivity in multidrug-resistant Mycobacterium tuberculosis putatively by inhibiting efflux pumps Rv0194 and Rv0933.

Multidrug-resistant tuberculosis remains a global health challenge, necessitating novel therapeutic approaches. Efflux pumps, including Rv0194 and Rv0933, contribute to Mycobacterium tuberculosis resistance by actively extruding first-line drugs such as rifampicin and isoniazid. This study aimed to identify small-molecule inhibitors that target these pumps to restore drug susceptibility. Through in silico screening, six lead compounds were selected and evaluated for antimicrobial activity against ten MDR-TB clinical isolates. Among them, flurbiprofen and trichlorocarbinalide exhibited significant inhibitory effects, enhancing rifampicin and isoniazid activity in checkerboard synergy assays. These combinations reduced the minimum inhibitory concentrations of both drugs, confirming their potential to reverse resistance. Cytotoxicity assessments of peripheral blood mononuclear and THP-1 cells demonstrated favourable safety profiles. Mechanistic studies revealed increased expression of Rv0194 and Rv0933 upon rifampicin and isoniazid exposure, underscoring their role in drug resistance. Flurbiprofen and trichlorocarbinalide may enhance intracellular drug retention by inhibiting these efflux pumps, improving therapeutic efficacy. However, trichlorocarbinalide did not restore rifampicin or isoniazid sensitivity as efficiently as flurbiprofen did. These findings highlight flurbiprofen as a promising efflux pump inhibitor that could potentiate standard TB treatments and counteract resistance. Further studies using diverse clinical isolates and in vivo models are needed to validate its therapeutic potential.