Evaluation of two formulations of dihydrocodeine using patient-controlled analgesia.

A randomised, double-blind study of 90 patients after cardiac bypass surgery was undertaken to assess the relative analgesic efficacies of normal- and controlled-release oral dihydrocodeine. Patients received either placebo, normal-release dihydrocodeine, or controlled-release dihydrocodeine at regular intervals on the first to third days after operation. This was supplemented in all groups by intravenous morphine administered on demand by a patient-controlled analgesia system. Morphine requirements in the control group were significantly greater during this 48-hour period than in either of the active groups (p less than 0.01), but there was no statistically significant difference between the two active preparations.