The purpose of this study is to determine how many HIV-infected patients continue taking ritonavir/indinavir combination after having taken indinavir three times a day as part of their anti-HIV drug therapy. This study also examines the safety and effectiveness of the ritonavir/indinavir combination.

Inclusion Criteria

Patients must have:

• HIV infection.
• CD4 cell count greater than 100 cells/microliter.
• HIV RNA levels greater than 400 copies/microliter using the Roche Ultrasensitive assay.
• No acute illness.
• Consent of parent or guardian if less than legal age.
• No prior enrollment in this study.
• All entry criteria for this study met within 15 days prior to enrollment.

Exclusion Criteria

Co-existing Condition:

Patients with any of the following symptoms or conditions are excluded:

Any condition that in the opinion of the investigator may obscure proper observation of the safety or activity of the treatment regimens used in this study.

Concurrent Medication:

Excluded:

• Concurrent non-nucleoside reverse transcriptase inhibitors as part of the antiretroviral regimen.
• Any of the following medications with ritonavir:
• midazolam, clorazepate, diazepam, estazolam, flurazepam, triazolam, zolpidem, quinidine, amiodarone, encainide, flecainide, propafenone, bepridil, terfenadine, astemizole, cisapride, bupropion, clozapine, rifabutin, meperidine, propoxyphene, piroxicam, pimozide, dihydroergotamine, and ergotamine.
• Any of the following medications with indinavir:
• terfenadine, astemizole, cisapride, triazolam, midazolam. No requirement for rifampin or ketoconazole.
• Any concurrent treatment with other protease inhibitors.
• Other concurrent medication (including over-the-counter medicine or alcohol) without the knowledge and permission of the primary investigator.

Patients with the following prior conditions are excluded:

• History of significant drug hypersensitivity.
• Psychiatric illness that precludes compliance with the protocol.
• Receipt of investigational drug within 30 days prior to administration of study drug.
• History of acute or chronic pancreatitis.
• Anticipation of poor patient compliance with protocol.

Prior Medication:

Excluded:

Prior treatment with ritonavir.

Risk Behavior:

Excluded:

History of active substance abuse (i.e., recreational drugs or alcohol).

Included:

- Indinavir 800 mg three times a day plus unspecified nucleosides for at least 3 months.