Steady-state pharmacokinetics and pharmacodynamics in methadone maintenance patients: Comparison of those who do and do not experience withdrawal and concentration-effect relationships

Abstract

In this group of long-term methadone-maintained recipients, opioid responses were strongly correlated with changes in plasma racemic methadone concentrations. For the subjective responses, notably withdrawal, small changes in plasma concentrations translate into relatively large changes in effect; therefore, clinically important withdrawal is a consequence of more rapid decline in methadone concentration.