Effects of methadone on liver enzymes in patients undergoing methadone maintenance treatment

Methadone is currently the most frequently used substance in the treatment of short-term and particularly long-term opiate dependence. Patients' beliefs about the adverse effects of methadone on function of organs, especially liver, have widely affected the use of this substance. This study aimed to determine the effects of methadone on liver enzyme levels in patients on methadone maintenance treatment.

In a retrospective study, a total of 94 patients undergoing methadone maintenance therapy were recruited from Shahid Beheshti Hospital (Kerman, Iran). Liver enzyme levels in all patients were tested every six months from the onset of treatment until 24 months. The relations between test results and age, gender, and methadone dose were then evaluated. Data was analyzed using logistic regression with random data plan.

At the 24th month, alanine aminotransferase (ALT) levels in 4 patients (4.3%) and aspartate aminotransferase (AST) levels in 3 patients (3.2%) were above normal. Among 46 patients (50%) who had normal alkaline phosphatase (ALP) levels after 24 months, 26 subjects were younger than 40 and 20 subjects were over 40 years of age. The mean age of subjects with abnormal ALP levels and the mean methadone dose were 39.9 years and 19.55 cc, respectively.

The results of this study indicated the significant effect of methadone on ALP levels. These effects can account for cholestatic pattern liver injury (obstruction). Further prospective studies including greater samples of patients with heart and liver complications and encompassing other drugs are required to confirm our findings.