Methadone disposition in patients with chronic liver disease.

Chronic liver disease is common in methadone-maintained patients. We studied the disposition of this drug in 14 patients with biopsy-proved chronic liver disease and five otherwise healthy subjects receiving methadone maintenance treatment. The patients were divided into three groups based on the severity of liver disease, with group I having the most severe disease. The apparent terminal half-life of methadone was longer in group I than in group II and III (moderate and mild chronic liver disease, P less than 0.01) and the contrast group (P less than 0.05). All other kinetic indices determined for group I and all kinetic indices in groups II and III were essentially the same as those in the contrast subjects or in the other patient groups. Seven patients, including al five in group I, had flattened plasma methadone concentration-time curves. The data suggest that the maintenance dosage of methadone need not be changed in stable chronic liver disease.