“ Methadone metabolism was 60-72% inhibited either by three mechanism-based inhibitors of P450 3A4 (gestodene, TAO, and erythralosamine) or by four reversible inhibitors of P450 3A (ketoconazole, dihydroergotamine, quercetin , and diazepam with an apparent Ki of 50 microM) and by two nonspecific inhibitors (metyrapone and SKF-525A).”