[Develop rapid and inexpensive method for the determination of methadone and its major metabolites for monitoring therapy].

Methadone maintenance therapy is one of the most popular treatments for opiate addiction. The easiest and the most reliable way to monitor the accuracy of the therapy is determination of methadone and its metabolites in biological material. The aim of this study was to develop rapid and inexpensive method for the determination of methadone and its major metabolites--EDDP and methandol in drug concentration monitoring therapy and to check its suitability to real samples collected from the patients, who participated in methadone maintenance therapy. The method is characterized by a wide range of linearity--from 50 to 1000 ng/ml for methadone and methadole, and from 20 to 600 ng/ml for EDDP. The lower limit of quantification for methadone and methadole was 50 ng/ml and for 20 ng/ml for EDDP. The repeatability of the method during the day and between days is below 10%. The method allows the determination of minimum concentrations of methadone (before the next dose) in patients treated with standard doses (40-120 mg/day) of this medicine. Different concentration ratios of metabolites to parent drug prove that the polymorphic metabolism leads both to the EDDP, methadone and methadole.