Pharmacokinetic Study of Interaction Between Nevirapine and Methadone in HIV-1 Infected, Opioid-dependent Adults

Inclusion criteria: * Treatment-naïve, fulfilling standard criteria to commence antiretroviral therapy. Previous exposure to less than two weeks of nucleoside reverse transcriptase therapy was permitted. (Later amended to allow previous exposure to non-nucleoside reverse transcriptase inhibitor therapy (NNRTI) if the patient was off NNRTI therapy for at least two weeks prior to entry.) * Plasma HIV-1 ribonucleic acid (RNA) assay performed at screening documenting HIV-1 infection or previous laboratory documentation of HIV-1 positive status. CD4+ cell count at least 100 cells/mm3 (later amended to at least 50 cells/mm3), within 28 days prior to study day 0. * Patients who met the following laboratory parameters: * Lymphocyte count at least 1 x 109/L * Haemoglobin at least 5.7 mmol/L \[9.0 g/dL\] (men and women) * Platelet count at least 75 x 109/L * Alkaline phosphatase less than or equal to 3 times the upper limit of normal * Serum glutamate oxaloacetate transferase (SGOT) and serum pyruvate oxaloacetate transferase (SGPT) less than or equal to 3 times the upper limit of normal * Total bilirubin less than or equal to 1.5 times the upper limit of normal * Serum creatinine less than or equal to 2.0 mg/dL. * On stable methadone maintenance therapy for at least five days prior to entry. * Patients of reproductive potential must have been willing to use a reliable method of double-barrier contraception (such as a diaphragm with spermicidal cream or jelly, or condoms with spermicidal foam). * Informed of, and willing and able to comply with the investigational nature of the study, and have signed a written consent in accordance with ethics committee and regulatory guidelines. Exclusion criteria: * Female patients who were pregnant or breast-feeding. * Systemic treatment with corticosteroids or drugs known to be hepatic enzyme inducers or inhibitors within 14 days of study entry. Substances in these categories include macrolide antibiotics (e.g. erythromycin, clarithromycin), azole antifungals (e.g. ketoconazole, fluconazole, itraconazole), rifampin, rifabutin, and phenytoin. * Treatment with any investigational drug within 30 days of the first dose of study medication, and any neoplastic agent or radiotherapy other than local skin radiotherapy treatment within 12 weeks before starting study medication. * Malabsorption, severe chronic diarrhoea or unable to maintain adequate oral intake. * Treatment for an active infection (secondary to HIV-1). * Hepatic insufficiency due to cirrhosis. * Renal insufficiency. * Excessive alcohol intake. * Treatment with ritonavir. * Treatment with protease inhibitors.