Inclusion Criteria

Prior Medication:

Allowed:

• Prophylaxis for Pneumocystis carinii pneumonia (PCP); zidovudine.

Unequivocal diagnosis of Pneumocystis carinii pneumonia (PCP) established by morphological confirmation of three or more typical Pneumocystis carinii organisms in bronchoalveolar lavage fluid, obtained immediately following the initial inhalation of radiolabeled aerosol.

• Resting (A-a) DO2 < 30 torr on room air or resting (A-a) DO2 = or < 55 torr on room air with a serious intolerance to trimethoprim / sulfamethoxazole (TMP / SMX), defined as one or more of the following:
• Platelets < 50000 platelets/mm3 or absolute neutrophil count (polys plus bands) = or < 500 cells/mm3 on at least two occasions = or > 12 hours apart.
• Blistering rash, mucosal involvement, generalized maculopapular eruption, or intolerable pruritus.
• Transaminase > 5 x ULN or = or > 300 IU if baseline is abnormal.
• Daily temperature = or > 103 degrees F beginning after the 5th day of treatment and persisting for at least 3 days and not responsive to antipyretic therapy, with no other discernible cause.
• Any other severe or life-threatening adverse reaction to TMP / SMX that, in the investigator's opinion, makes continued or recurrent treatment with TMP / SMX inadvisable (approved on a case-by-case basis by the NIAID clinical monitor).

Exclusion Criteria

Co-existing Condition:

Patients with the following conditions or diseases are excluded:

• Dyspnea, cough, bronchospasm, or other reasons causing inability to cooperate with aerosol administration.
• History of major adverse reaction to pentamidine.

Patients with the following conditions or diseases are excluded:

• Dyspnea, cough, bronchospasm, or other reasons causing inability to cooperate with aerosol administration.
• History of major adverse reaction to pentamidine.

Prior Medication:

Excluded:

• Other antiprotozoal regimens.
• Excluded within 14 days of entry:
• Systemic steroids > adrenal replacement doses