Use of trimethoprim-sulfamethoxazole in the treatment of Pneumocystis carinii pneumonitis in patients with acquired immunodeficiency syndrome.

This report reviews the use of trimethoprim-sulfamethoxazole (TMP-SMZ) in individuals with Pneumocystis carinii pneumonitis (PCP) and the acquired immunodeficiency syndrome (AIDS). Before AIDS, TMP-SMZ was at least as effective as pentamidine in pediatric and adult populations and was notably less toxic. In a study prospectively comparing TMP-SMZ with pentamidine in patients with AIDS, the toxicity associated with either therapy was very high, a problem suggesting a need for the development of additional types of therapy. There was no difference in the clinical responses to the different therapeutic regimens; the majority of patients showed some improvement. The rates of both major and minor toxic reactions were similar in the two groups, although the reactions differed qualitatively. In patients with AIDS rash was frequently associated with TMP-SMZ therapy and was almost never associated with pentamidine therapy. Neutropenia was common with both drugs. Pentamidine may produce hypoglycemia, which, though infrequent, may be life threatening. Neutropenia and rash are two adverse effects of TMP-SMZ therapy being described with great frequency in patients with AIDS. Mild neutropenia is common in patients with AIDS, even when therapy is not being administered. The high rate of toxic reactions limits the usefulness of TMP-SMZ for routine prophylaxis.