PATIENT-CONTROLLED ANALGESIA (PCA) WITH CODEINE FOR POSTOPERATIVE PAIN RELIEF IN 10 EXTENSIVE METABOLIZERS AND ONE POOR METABOLIZER OF DEXTROMETHORPHAN

Postoperative pain relief with codeine was evaluated in 11 women under going hysterectomy. Patient-controlled analgesia (PCA) was used to adm inister codeine. After the study the patients were phenotyped with res pect to the O-demethylation of dextromethorphan (cytochrome P4502D6 po lymorphism). Ten were extensive metabolisers and one a poor metabolise r. There was a nine-fold variation in the minimum plasma concentration of codeine consistent with pain relief (40-350 ng ml(-1)). Two patien ts did not experience any effect of codeine, one of whom was a poor me taboliser of dextromethorphan, confirmed by genotyping. In the other n ine patients the effective dose of codeine varied from 4.8-25.3 mg h(- 1).