To assess the safety and pharmacokinetics of single oral doses of 524W91 administered in HIV-infected patients. To determine the effects of food on bioavailability of 524W91.

Patients are randomized to receive six single escalating doses of 524W91 or placebo, with each dose separated by at least a 6-day washout interval. In the time between 2 of the doses, the effect of food on pharmacokinetics will be investigated, with one dose administered in conjunction with a high-fat meal and one dose administered in a fasted state.

Inclusion Criteria

Patients must have:

• Documented HIV infection.
• CD4 count >= 200 cells/mm3.
• No active opportunistic infection.

Exclusion Criteria

Co-existing Condition:

Patients with the following symptoms or conditions are excluded:

• Malignancy or other condition that would confound study assessment or interfere with ability to complete the study.
• Malabsorption syndrome or other gastrointestinal dysfunction that might interfere with gastrointestinal absorption.

Concurrent Medication:

Excluded on the day of each dose:

• Antiretrovirals.
• Any prescription or over-the-counter medication.
• Alcoholic beverages.
• Coffee, tea, and other xanthine-containing beverages and foods.

Patients with the following prior conditions are excluded:

History of hepatitis, pancreatitis, or cardiomyopathy within the past 5 years.

Prior Medication:

Excluded:

• Antiretrovirals within 24 hours prior to each dose.
• Any prescription or over-the-counter medications within 48 hours prior to each dose.
• Alcoholic beverages within 48 hours prior to each dose. Current alcohol or illicit drug use that may affect patient compliance.