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