Patients receive MK-639 for 14 and one-third days. Repeat plasma samples are collected up to 8 hours following the first and last dose. Urine samples are collected on days 1 and 5.

Inclusion Criteria

Patients must have:

• HIV positivity.
• No active opportunistic infection within the past 30 days, other than superficial candidiasis of the oral cavity or vagina.
• Body surface area at least 1.0 sqm.
• Consent of parent or guardian.

Prior Medication:

Allowed:

• Aerosolized pentamidine.
• Topical antifungals.
• TMP / SMX.
• AZT.

Exclusion Criteria

Co-existing Condition:

Patients with the following symptoms or conditions are excluded:

• Significant hepatic disease including HBsAg or hepatitis C positivity.
• Significant neurologic disease such as loss of intellectual ability, motor deficits, or seizure disorder.
• Significant cardiac disease including dysrhythmia or cardiomyopathy.
• Significant medical condition or laboratory abnormality that may pose additional risk to patient on study or confound the results.
• Has a social situation that may interfere with study participation.

Concurrent Medication:

Excluded:

• Oral contraceptives.

Patients with the following prior conditions are excluded:

• History of serious allergic drug reactions.
• History of significant cardiac disease.
• Participation on another clinical trial within the past 4 weeks.
• Donated blood within the past 4 weeks.

Prior Medication:

Excluded within the past 4 weeks:

• Hematopoietic growth factors.

Excluded within the past 2 weeks:

• Antiretroviral agent other than zidovudine.
• Oral contraceptives.
• Prophylaxis for opportunistic infections, other than aerosolized pentamidine, topical antifungals, and TMP/SMX.
• Any other medication unless approved by Merck clinical monitor. Current illicit drug use.