Once-a-month administration of intravenous pentamidine to patients infected with human immunodeficiency virus as prophylaxis for Pneumocystis carinii pneumonia.

We reviewed the charts of 52 patients infected with human immunodeficiency virus (HIV) who received at least three consecutive doses of intravenous pentamidine as prophylaxis for Pneumocystis carinii infections. Pentamidine isethionate was administered intravenously over 60-90 minutes once a month, at a dosage of 4 mg/kg, in 250 mL of 5% dextrose in water. During 387 months of administration of primary prophylaxis to 37 patients, no cases of P. carinii pneumonia were observed. During 200 months of administration of secondary prophylaxis to 15 patients, only one case of P. carinii pneumonia was diagnosed (6.0 cases per 100 patient-years). Side effects associated with the intravenous pentamidine were mild and did not necessitate withdrawal of the drug. Once-a-month administration of intravenous pentamidine is a valid alternative as prophylaxis for P. carinii pneumonia for patients who are intolerant of sulfonamides.