A Double-Blind Group Comparative Study To Evaluate the Long-Term Safety and Effectiveness of Two Different Doses of Aerosol Pentamidine in the Prophylaxis of Pneumocystis Carinii Pneumonia in AIDS Patients With Multiple Episodes of PCP

Inclusion Criteria Concurrent Medication: Allowed: Zidovudine (AZT). Patients must have: AIDS. Recovered from their most recent episode of Pneumocystis carinii pneumonia (PCP). Patients must be at least 2 weeks status post therapy for acute PCP. Adequate pulmonary function (vital capacity = or > 65 percent of predicted; forced expiratory volume, 1 s = or > 55 percent of total FEV; and corrected pulmonary diffusion capacity > 50 percent of predicted). Patients must be free of acute medical problems. Exclusion Criteria Co-existing Condition: Patients with the following are excluded: AIDS-defining opportunistic infection prior to entry such as toxoplasmosis and cryptococcosis. Pulmonary Kaposi's sarcoma. Asthma poorly controlled by medication. Receiving active therapy for tuberculosis. Concurrent Medication: Excluded: Active therapy for tuberculosis. Patients with the following are excluded: Requiring ongoing active therapy for an opportunistic infection at time of study entry. AIDS-defining opportunistic infection prior to study entry such as toxoplasmosis and cryptococcosis. Pulmonary Kaposi's sarcoma. Unwilling to sign informed consent. Asthma poorly controlled by medication. Unwilling to cooperate with study procedures. Receiving active therapy for tuberculosis. Prior Medication: Excluded within 30 days of study entry: Antiretrovirals (other than zidovudine (AZT)). Immunomodulating agents. Corticosteroids. Prior Treatment: Excluded within 7 days of study entry: Transfusion. Patient cannot be transfusion dependent (requiring blood transfusion more than once per month). Active substance abuse.