AVAILABILITY OF RELIABLE SERUM METHADONE DETERMINATION FOR MANAGEMENTOF SYMPTOMATIC PATIENTS

Methadone, when used in the appropriate dose, prevents opioid withdraw al during the 24-hour period following medication However, the appropr iate dose for a given patient may be difficult to determine due to var iations in methadone metabolism which is affected by many factors. Ear ly opioid withdrawal, requiring a higher dose of methadone, is often d ifficult to diagnose because many of the symptoms are also symptoms of other syndromes common in the methadone maintenance population. In th is study, ten patients in stable methadone maintenance treatment repor ting greater than or equal to 4 Himmelsbach signs of abstinence were c ompared with ten-patients reporting fewer symptoms. Until recently acc urate, precise, and affordable determination of serum methadone level has not been readily available from commercial laboratories. This stud y has found that such measures are now available. Serum specimens from each subject were sent to three commercial laboratories for determina tion of serum methadone level. Results from the three laboratories wer e highly correlated. No statistical correlation was found between seru m methadone level and number of Himmelsbach signs. Of the subjects rep orting four or more symptoms, 40% had low serum methadone levels (< 15 0 ng/ml); 60% did not. Of the subjects reporting fewer than four sympt oms, 90% had serum methadone levels greater than or equal to 150 ng/ml . Subjects with greater than or equal to 4 Himmelsbach signs had lower dose-adjusted serum methadone levels, the amount of methadone circula ting per mg dose, (t = 1.54, p < .0702). Thus, for patients who report symptoms which could be attributable to opioid withdrawal, measuremen t of serum methadone level may help to differentiate complaints due to early abstinence from those due to other medical conditions.