Emetic effects of morphine and piritramide

Background. Successful management of postoperative pain requiresthat adequate analgesia is achieved without excessive adverseeffects. Opioid-induced nausea and vomiting is known to impairpatients’ satisfaction, but there are no studies providingsufficient power to test the hypothesis that the incidence ofopioid-induced nausea and vomiting differs between µ-opioidreceptor agonists. Thus, we tested the hypothesis that the incidenceof vomiting and nausea differs between morphine and piritramide. Methods. In a prospective, randomized, double-blind fashion,we administered either morphine (n=250) or piritramide (n=250)by patient-controlled analgesia (PCA) for postoperative painrelief. We used a bolus dose of 1.5 mg with a lockout time of10 min. Incidence and intensity (numerical rating scale) ofpostoperative nausea, vomiting, pain, patient satisfaction (score0–10), side-effects (score 0–3) and drug consumptionwere measured. Results. Mean drug consumption did not differ between the piritramideand morphine groups (30.8 (SD 22.4) mg day^–1 vs 28.4 (21.8)mg day^–1) during the first postoperative day and therewere no significant differences in the overall incidence ofnausea (30% vs 27%) and vomiting (19% vs 15%). Intensity ofnausea correlated inversely (P=0.01) with morphine consumptionbut not with piritramide consumption. Pain scores both at rest(2.2 (1.9) vs 2.6 (2)) and during movement (4.4 (2.2) vs 4.9(2.3)) were slightly but significantly less with morphine. Conclusions. Opioid-induced emesis was observed in about one-thirdof the patients using morphine and piritramide for PCA and theincidence of vomiting was one-half of that. Potential differencesin the incidence of vomiting during PCA therapy between theseµ-opioid receptor agonists can be excluded. Br J Anaesth 2003; 91: 218–23