Efficacy of sulfamethoxypyridazine in a murine model of Pneumocystis carinii pneumonia.

Sulfamethoxazole is the component of co-trimoxazole responsible for its efficacy against Pneumocystis carinii pneumonia, but this drug is associated with frequent adverse effects. Sulfamethoxypyridazine is significantly more effective than sulfamethoxazole against a murine model of P. carinii and might be a candidate for testing in infected patients.