Studies on antituberculotic action of some phenothiazine derivatives in vitro

Five phenothiazine derivatives (chlorpromazine, levomepromazine, diethazine, promethazine and chlorpromazine) sulphoxyde were tested for antimycobacterial activity. The growth of Mycobacterium tuberculosis, M. bovis and M. butyricum was inhibited by chlorpromazine practically at identical concentrations. The minimum inhibitory concentrations for M. tuberculosis were: chlorpromazine and levomepromazine, 10 microgram/ml; diethazine and promethazine 20 microgram/ml, whilst chlorpromazine sulphoxyde was ineffective even at a concentration of 100 microgram/ml. Chlorpromazine and promethazine exerted a measurable bactericidal activity on M. tuberculosis at 50 microgram/ml; total destruction of the organism and loss of acid fastness in part of the cells were shown at 300 microgram/ml. Preliminary studies, in mouse experiments phenothiazine derivatives were ineffective.