A Controlled Comparative Trial of Trimethoprim - Sulfamethoxazole Versus Aerosolized Pentamidine for Secondary Prophylaxis of Pneumocystis Carinii Pneumonia in AIDS Patients Receiving Azidothymidine (AZT)

Inclusion Criteria Patients must fulfill the following criteria: Randomization within 10 weeks of completing therapy for Pneumocystis carinii pneumonia (PCP). Ability to tolerate oral and aerosolized therapy at the time of randomization. Life expectancy > 4 months. Concurrent Medication: Allowed: Inhaled bronchodilators for cough and bronchospasm related to aerosolized pentamidine treatment. Aspirin at modest doses. Ibuprofen at modest doses. Acetaminophen at modest doses. Erythropoietin for management of anemia. Allowed to treat opportunistic infections while on study: Acyclovir. Ketoconazole. Amphotericin B. Nystatin. Clotrimazole. Also allowed: Ganciclovir (DHPG) for maintenance therapy of life-threatening or sight-threatening cytomegalovirus retinitis (CMV retinitis) infection only. Zidovudine (AZT) must be discontinued during the acute induction phase of treatment and will be restarted when maintenance therapy is introduced. Concurrent Treatment: Allowed: Local radiation therapy for Kaposi's sarcoma. Prior Medication: Allowed: Primary prophylactic therapy prior to Pneumocystis carinii pneumonia (PCP) episode. Risk Behavior: Allowed: Patients maintained in a methadone maintenance program per local investigator's judgment. Exclusion Criteria Active drug or alcohol abuse which would impair performance as a study subject. Concurrent Medication: Excluded: Famotidine. Any medications suspected of interference with the metabolism of zidovudine. Flurazepam. Chronic probenecid. Phenobarbital. Phenytoin. Experimental therapies, except as noted. Chronic oral bronchodilators should not be started in patients in order to maintain them on aerosolized pentamidine after they have exhibited pulmonary toxicity. Prior Medication: Excluded for the 30 patients who will undergo pharmacokinetic studies: Zidovudine (AZT) at any time. Excluded within 7 days of study entry for the 30 patients who will undergo pharmacokinetic studies: Trimethoprim / sulfamethoxazole. Pyrimethamine / sulfadoxine. Aerosolized pentamidine. Excluded: Pentamidine by any route for the original infection. Prophylactic therapy for Pneumocystis carinii pneumonia (PCP) between the discontinuation of acute treatment and study entry. Prior Treatment: Excluded within 2 weeks of study entry: Transfusions of blood or red blood cells. Patients may not have any of the following symptoms or diseases: Known treatment-limiting hypersensitivity to sulfonamides, trimethoprim, pyrimethamine, pentamidine, or zidovudine (AZT), especially but not limited to, exfoliative dermatitis, erythema multiforme, and Stevens-Johnson syndrome. Development of severe hypoglycemia (serum glucose < 50 mg/dl with pentamidine therapy). History of neoplasms other than basal cell carcinoma of the skin or carcinoma in situ of the cervix, or mucocutaneous Kaposi's sarcoma. Known visceral Kaposi's sarcoma. Known glucose-6-phosphate dehydrogenase (G-6-PD) deficiency.