Synthesis and synergistic antimycobacterial screening of chlorpromazine and its metabolites

The antimycobacterial activities of chlorpromazine and its metabolites were evaluated alone and in combination with antitubercular drugs. Although associated with limited antimycobacterial activity when tested individually, chlorpromazine and its metabolites exhibited clear synergy when tested in combination with a number of aminoglycosides as well as the active metabolite of rifampicin, 25-desaceteylrifampicin. The combination of chlorpromazine and spectinomycin was associated with the greatest synergy, yielding a fractional inhibitory concentration index (FICI) of 0.31. Synergistic interactions were also observed for combinations of 7-hydroxychlorpromazine or nor-chlorpromazine with kanamycin, streptomycin, spectinomycin and 25-desacetylrifampicin (FICI 0.19–0.5).