Correlation between high methadone doses and methadone serum levels in methadone maintenance treatment (MMT) patients.

AIMS: To evaluate the relation between high methadone doses and methadone serum levels in MMT patients.

DESIGN: One hundred fifty-one steady methadone-dose patients were evaluated for methadone serum levels using GCMS. Urine samples during the month prior to the study-day were analysed and defined as positive if any sample was positive for any drug.

FINDINGS: Methadone dose correlated with methadone serum levels (Pearson R = 0.36, P < 0.0005). In 53 patients with no drug abuse, correlation was stronger (R = 0.53, P < 0.0005) than in 98 patients with any drug abuse (R = 0.25, P = 0.01).

CONCLUSIONS: We extended the well-established correlation between methadone doses and serum levels in patients receiving low or moderate (60 to 120 mg/day) to high methadone doses (up to 290 mg/day).