Inclusion Criteria

Concurrent Medication:

Allowed:

• Pentamidine or dapsone prophylaxis for Pneumocystis carinii pneumonia (PCP) in patients with a CD4+ cell count = or < 200 cells/mm3.
• Antifungal prophylaxis with oral fluconazole or ketoconazole.
• Antiviral prophylaxis with a maximum of 1 gram of oral acyclovir per day.
• Acute therapy for intercurrent infections so long as that therapy is not an excluded medication of an excluded opportunistic infection.

Patients must have:

• Positive HIV antibody test results by ELISA.
• Average of CD4+ cell count at 60 and at 21 days prior to study beginning = or < 400 cells/mm3.
• Seven of 10 patients in each treatment arm must have p24 antigen levels = or > 70 pg/ml (> 50 pg/ml at U. of Mass. site only) or be plasma viremic.
• Preserved hematologic, hepatic, and renal function as defined by required lab values.
• Ambulatory performance score of = or > 70 Karnofsky.
• Ability to voluntarily provide written informed consent prior to treatment.
• Willingness and ability to follow protocol requirements.

Exclusion Criteria

Co-existing Condition:

Patients with the following symptoms or conditions are excluded:

• Active cytomegalovirus disease.
• Toxoplasmic encephalitis requiring suppressive therapy.
• Mycobacteriosis requiring maintenance chemotherapy.
• Visceral Kaposi's sarcoma requiring chemotherapy and/or irradiation.
• Malignancy other than Kaposi's sarcoma or limited cutaneous basal cell carcinoma.
• More than mild diarrhea (defined as more than transient or > 4 loose stools per day).

Concurrent Medication:

The following medications / substances may NOT be ingested up to one hour before or 4 hours after a Nevirapine dose:

• Antacids (particularly those containing calcium carbonate).
• Cimetidine.
• Carafate.
• Cholestyramine resin.
• Alcohol and alcohol-containing substances.
• Benzodiazepines (diazepam, triazolam).

Excluded:

• Any approved or investigational antiretroviral, immunosuppressive, or cytotoxic drugs.
• Glucocorticoids and steroid hormones (including oral contraceptives).
• Dicumarol, warfarin, and other anticoagulant medications.
• Nitroglycerin.
• Digitoxin.
• Valproic acid.
• Tolbutamide.
• Doxycycline.
• Chloramphenicol.
• Isoniazid.
• Any sulfonamide medications.

Patients with the following are excluded:

• History of clinically important disease other than HIV infection defined by the investigator as possibly putting the patient at risk during study participation.
• Conditions listed in Exclusion Co-Existing Conditions and symptoms.
• Having received any approved or investigational antiretroviral, immunosuppressive, or cytotoxic drugs or any other experimental drug with 4 weeks of study entry.
• A positive zidovudine (AZT) detection assay performed 7 days prior to drug dosing will exclude patients from study participation.

Prior Medication:

Excluded within 4 weeks of study entry:

• Any approved or investigational antiretroviral, immunosuppressive or cytotoxic drugs.
• Glucocorticoids and steroid hormones (including oral contraceptives).
• Dicumarol, warfarin, and other anticoagulant drugs.
• Nitroglycerin. Digitoxin.
• Valproic acid.
• Tolbutamide.
• Doxycycline.
• Chloramphenicol.
• Isoniazid.
• Antiepileptics (phenobarbital and other barbiturates).
• Trimethoprim / sulfamethoxazole (Bactrim).

Risk Behavior:

Excluded:

• Patients whose use of alcohol or drugs is sufficient to impair compliance with protocol requirements.