Sensitivity to acute methadone dose changes in maintenance patients.

This study assessed whether methadone patients can identify acute dose changes in their maintenance dose, and explored the relationships between self-reported drug effects and real or perceived dose changes. Four times each week patients (N = 10) unpredictably received either 80%, 90%, 100%, 110% or 120% of their usual daily dose (50-100 mg). Approximately 24 hr later they indicated which dose they had received on the previous day, and rated the previous day's dose in terms of good effects, bad effects, and change in medication taste. Correct estimation of the doses received was always at the levels expected by chance alone. Furthermore, this sample of patients could not detect dose-related changes in medication taste. However, self-reports of good effects were significantly higher when patients believed that they had received a dose increment, and ratings of bad effects were higher when patients believed that they had received a dose decrement.