“Recently I’ve had patients write to my blog describing how their opioid treatment program doctors are using methadone blood levels to determine the correct dose. What they described to me was worrisome; patients’ doses rarely need to be checked with methadone peak or trough blood levels. Due to tolerance, a methadone blood level may be adequate for one patient, but far too low for other patients.
A patient’s dose of methadone needs to be determined on clinical grounds. This can include the patient’s description of withdrawal symptoms and their timing related to dosing, physical exam just before the patient is due for a dose, and evaluation of the patient three to four hours after dosing. It may also include an evaluation of ongoing illicit opioid use, other medical issues, and other medication or illicit drug use.”
Read more at: https://janaburson.wordpress.com/2015/04/19/confusion-over-methadone-peak-and-trough-levels/