Trimethoprim-sulfamethoxazole therapy for Pneumocystis carinii pneumonitis in children.

Trimethoprim-sulfamethoxazole (TMP-SMZ) is effective in both the treatment and the prevention of Pneumocystis carinii pneumonitis. After initial evaluation in an animal model, TMP-SMZ was shown to be as clinically effective as pentamidine isethionate for the treatment of pneumonitis in children with cancer and to have minimal adverse effects. Treatment with TMP-SMZ (20 mg of TMP and 100 mg of SMZ per kg of body weight per day) was successful in three-fourths of patients tested. Administered prophylactically, TMP-SMZ (5.0 mg of TMP and 25 mg of SMZ per kg of body weight per day) prevented P. carinii infection in high-risk immunocompromised patients. Studies of the unstructured delivery of prophylactic TMP-SMZ have demonstrated the regimen to be feasible and effective, with a favorable benefit-risk ratio for a large number of children with cancer.