Effect of trifluoperazine, a potential drug for tuberculosis with psychotic disorders, on the growth of clinical isolates of drug resistant Mycobacterium tuberculosis.

The effect of the antipsychotic drug trifluoperazine (TFP) on the in-vitro growth of 50 clinical isolates of Mycobacterium tuberculosis was tested. Of these isolates, 29 were susceptible to all five of the antitubercular drugs isoniazid, rifampicin, streptomycin, ethambutol and pyrazinamide, and 21 were resistant to one or more of the five drugs. The minimum inhibitory concentration (MIC) of TFP was 4 microg/ml for 40% of both the susceptible (12/29) and resistant (8/21) isolates and 8 microg/ml for 55% (16/29) and 48% (10/21) of the susceptible and resistant isolates respectively. Further analysis of the data for resistant isolates indicated that the MIC of TFP was 4 microg/ml and 16 microg/ml respectively for 50% (4/8) and 75% (6/8) of the isolates resistant to one drug only from isoniazid, streptomycin or pyrazinamide. Of the nine isolates resistant to two drugs, isoniazid and streptomycin, the MIC was 4 microg/ml for 33% (3/9) and 16 microg/ml for 80% (7/9). The MIC of TFP for two isolates resistant to the three drugs isoniazid, rifampicin and streptomycin was 8 microg/ml for one and 32 microg/ml for the other. Of two isolates resistant to all five drugs, it is of interest to note that the MIC of TFP was only 4 microg/ml for one but 32 microg/ml for the other. Because the above MICs are for TFP as a single drug, it would be desirable to study the antitubercular activity of the serum of tuberculosis patients with psychotic problems receiving regular antitubercular therapy supplemented with TFP at its recommended and tolerated dose.