title: The effect of ondansetron on the efficacy of postoperative tramadol: a systematic review and meta-analysis of a drug interaction.
abstract: Several studies have investigated the presence of a drug interaction between tramadol and ondansetron that reduced the efficacy of tramadol postoperatively. Most of these studies were small and the results inconsistent, so we performed a systematic review and meta-analysis of randomised controlled trials comparing the cumulative dose of tramadol administered by patient-controlled analgesia within the first 24 h after surgery between subjects receiving tramadol alone and those who received tramadol with ondansetron. Six studies, with a total of 340 participants, met the selection criteria and were included in the meta-analysis. There was an increased tramadol requirement in patients receiving ondansetron. The standardised mean difference in tramadol requirements, expressed in terms of standard deviations (95% CI), was 1.03 (0.54-1.53) (p < 0.001) at 4 h, 0.66 (0.06-1.25) (p = 0.03) at 8 h, 0.86 (0.41-1.31) (p < 0.001) at 12 h and 0.45 (0.01-0.90) (p = 0.046) at 24 h postoperatively, where the mean pooled standard deviations were 79.5, 157.7, 238.1 and 289.4 mg at 4, 8, 12 and 24 h, respectively. There was a significant linear time effect over the 24 h, indicating that the effect of ondansetron on tramadol consumption diminished with time. The results support the presence of a drug interaction between tramadol and ondansetron in the early postoperative period that potentially decreases the effectiveness of tramadol.
authors.affiliation: Flinders University, Bedford Park, South Australia, Australia.
authors.forename: A J
authors.initials: AJ
authors.lastname: Stevens
authors.forename: R J
authors.initials: RJ
authors.lastname: Woodman
authors.forename: H
authors.initials: H
authors.lastname: Owen
mesh_terms: D016058:Analgesia, Patient-Controlled / Q000379:methods; D000701:Analgesics, Opioid / Q000494:pharmacology*; D000932:Antiemetics / Q000494:pharmacology*; D004347:Drug Interactions; D006801:Humans; D017294:Ondansetron / Q000494:pharmacology*; D010149:Postoperative Pain / Q000188:drug therapy*; D020250:Postoperative Nausea and Vomiting / Q000188:drug therapy; D011184:Postoperative Period; D016032:Randomized Controlled Trials as Topic / Q000379:methods / Q000706:statistics & numerical data; D014147:Tramadol / Q000008:administration & dosage / Q000494:pharmacology*; D016896:Treatment Outcome
chemical_list: D000701:Analgesics, Opioid; D000932:Antiemetics; D014147:Tramadol; D017294:Ondansetron