The purpose of this study is to see if it is safe and effective to give ritonavir plus nelfinavir to HIV-infected patients. This study will also see how ritonavir and nelfinavir are absorbed by the body and how they affect the level of HIV in the blood.

Inclusion Criteria

Patients must have:

• Documentation of a positive ELISA test for HIV confirmed by immunoblot, or a positive HIV RNA test using the Roche PCR assay, or the Chiron bDNA assay.
• HIV RNA measurement of > 5,000 copies/ml within 3 weeks of baseline visit.
• Signed, informed consent from parent or legal guardian for patients less than 18 years of age.
• Access to a refrigerator for storing study drug.

Prior Medication:

Allowed:

Anti-HIV therapy other than protease inhibitor therapy.

Exclusion Criteria

Co-existing Condition:

Patients with the following conditions or symptoms are excluded:

• Evidence of acute infection, as measured by vital signs, physical examination, 12-lead electrocardiogram and laboratory assessments.
• Condition that may obscure the proper observation of the safety or activity of the treatment regimens.

Concurrent Medication:

Excluded:

• Midazolam, alprazolam, clorazepate, diazepam, estazolam, flurazepam, triazolam, zolpidem, quinidine, amiodarone, encainide, flecainide, propafenone, bepridil, terfenadine, astemizole, cisapride, bupropion, clozapine, rifabutin, meperidine, propoxyphene, piroxicam, pimozide, ergotamine, dihydroergotamine, and rifampin.
• Anti-retroviral therapy initiated prior to study entry.
• Any other medication, including over-the-counter medicine and alcohol, taken without the permission of the primary investigator.

Patients with the following prior conditions are excluded:

• History of significant drug hypersensitivity.
• History of psychiatric illness that would preclude compliance with the protocol.
• Prior enrollment in this study.

Prior Medication:

Excluded:

• Investigational drugs within 30 days prior to drug administration.

• Prior treatment with licensed or investigational HIV protease inhibitor.

  1. Active substance abuse.

• Positive urine screen for recreational drugs. NOTE:

• The presence of cannabis is not exclusionary unless the investigator believes its use will interfere with patient compliance.