Metyrapone-induced withdrawal symptoms

The metyrapone test is widely used in endocrinological testing to assess the integrity of hypothalamic-pituitary-adrenal axis function; we have used it to study the metabolic basis of addictive disease and opioid dependence. In recent studies, we have observed that metyrapone administration in long-term methadone-maintained patients and in patients undergoing slow dose reduction to drug-free status following chronic treatment may induce a narcotic withdrawal-like syndrome. Although metyrapone is known to produce mild adverse reactions in non-opiate dependent subjects, narcotic withdrawal-like symptoms have not been previously observed or reported. The metyrapone test was administered to 15 former heroin addicts: 10 (8 male, 2 female) in steady-state methadone maintenance therapy (30 to 90 mg/d) and 5 (3 male, 2 female) in the final phase of a slow methadone dose reduction procedure (0 to 10 mg/d). Eight out of 15 methadone maintenance subjects exhibited a narcotic withdrawal-like syndrome ranging from 'moderate' to 'severe' and four additional subjects had 'mild' symptoms, occurring within 1 h after metyrapone administration, and resolving within 2 h of onset. No significant symptoms were seen in 3 methadone maintained subjects nor in any of 9 normal volunteers (7 male, 2 female). The mechanism by which metyrapone induces symptoms resembling narcotic withdrawal in opiate-dependent individuals is unknown but physicians performing this test should be aware of this possible response.