Primary: To compare the pharmacokinetics of biweekly and monthly dose regimens of intravenous pentamidine in HIV-infected infants and children who require PCP prophylaxis and who are intolerant to oral trimethoprim - sulfamethoxazole. To determine the safety and tolerance of these regimens in this patient population.

Secondary: To obtain information on the rate of PCP breakthrough in infants and children receiving parenteral pentamidine prophylaxis.

Prophylaxis against Pneumocystis carinii pneumonia is recommended for all HIV-infected children considered to be at high risk. In children younger than 5 years of age with intolerance to trimethoprim - sulfamethoxazole, parenteral pentamidine may be a successful alternative.

Prophylaxis against Pneumocystis carinii pneumonia is recommended for all HIV-infected children considered to be at high risk. In children younger than 5 years of age with intolerance to trimethoprim - sulfamethoxazole, parenteral pentamidine may be a successful alternative.

Thirty-two children are randomized to one of two treatment arms. Patients receive pentamidine on either a biweekly or a monthly treatment schedule. Treatment continues until the last child enrolled has received at least 6 months of pentamidine. Patients are stratified according to age < 24 months or age >= 24 months. Steady-state pharmacokinetics will be examined in a subsample of 20 patients.

Inclusion Criteria

Concurrent Medication:

Allowed:

• Steroids and intravenous immune globulin (IVIG).

Patients must have:

• Documented HIV infection.
• Need for PCP prophylaxis.
• Known intolerance to trimethoprim - sulfamethoxazole (TMP-SMX).

One of the following required conditions:

• Known intolerance or allergy to dapsone; G6PD deficiency; history of serious or life-threatening reaction to TMP-SMX; exclusion from protocol ACTG 179; election by parent not to enroll child on ACTG 179; or receiving medical care at sites not participating in ACTG 179.

NOTE:

• Co-enrollment in other ACTG pediatric studies is permitted.

Consent of parent or guardian is required.

Prior Medication:

Allowed:

• Prior pentamidine.

Exclusion Criteria

Co-existing Condition:

Patients with the following symptoms and conditions are excluded:

• Active PCP.
• Pancreatitis defined as amylase elevation associated with an elevated lipase that is > 2 x upper limit of normal.

Prior Medication:

Excluded:

• TMP-SMX or dapsone within 7 days prior to study entry (toxicities to TMP-SMX or dapsone must be clearly resolving).