To evaluate the potential pharmacokinetic interaction between nevirapine and clarithromycin, and to determine the effects of nevirapine on cytochrome P450 3A4 (CYP3A4) activity in vivo.

The study is conducted in two separate groups. Patients in Group I receive clarithromycin orally for 32 days and nevirapine orally for 28 days.

Patients in Group II receive erythromycin intravenously on days 0, 14, 28, and 43 and nevirapine orally for 28 days.

Inclusion Criteria

Concurrent Medication:

Allowed:

Antiretroviral drugs (i.e., zidovudine, zalcitabine, stavudine, lamivudine, didanosine, indinavir, saquinavir) provided that there has been no change in dosing of the medication > 25% within 4 weeks of study entry.

Patients must have:

• HIV positive status.
• CD4 count >= 100 cells/mm3.

Prior Medication:

Allowed:

Patients may be on clarithromycin at study entry.

Exclusion Criteria

Co-existing Condition:

Patients with the following conditions are excluded:

Malabsorption, severe chronic diarrhea, or inability to maintain adequate oral intake.

Concurrent Medication:

Excluded:

Macrolide antibiotics (erythromycin, azithromycin, dirithromycin), azole fungals (ketoconazole, fluconazole, itraconazole), rifampin, rifabutin, phenytoin, terfenadine, astemizole, cisapride, triazolam, midazolam, other non-nucleoside reverse transcriptase inhibitors, antibiotics containing clavulanic acid, and Augmentin.

Patients with the following prior conditions are excluded:

• History of drug allergy or known drug hypersensitivity.
• History of clinically important disease including hepatic, renal, cardiovascular, or gastrointestinal disease.

Prior Medication:

Excluded:

• Investigational drugs or antineoplastic agents within 12 weeks of study entry.
• Participation in a clinical trial that used ERMBY within one year of study entry.
• Systemic treatment with drugs known to be potent hepatic enzyme inducers or inhibitors (e.g., oral macrolide antibiotics, azole antifungals, cimetidine, rifampin, rifabutin, and carbamazepine) within 28 days of study entry.
• Use of protease inhibitors; ritonavir, nelfinavir, indinavir, or non-nucleoside reverse transcriptase inhibitor compounds e.g., delavirdine) within 4 weeks of study entry.

Prior Treatment:

Excluded:

Radiotherapy within 12 weeks of study entry.

Risk Behavior:

Excluded:

Current history (within the last year) of IVDA, ETOH, or substance abuse.