Successful treatment and prevention of murine Pneumocystis carinii pneumonitis with 4,4'-sulfonylbisformanilide.

Pneumocystis carinii pneumonitis was prevented in 0, 50, 100, and 100% of immunosuppressed rats given doses of 0.5, 5.0, 25.0, and 125.0 mg/kg (body weight) per day, respectively, of 4,4'-sulfonylbisformanilide (DFD). Therapeutic efficacy was demonstrated with DFD at 25.0 mg/kg per day, and when this dose was combined with trimethoprim, the combination was as effective as trimethoprim-sulfamethoxazole, which has been proven to be effective in the treatment of murine and human P. carinii pneumonitis.