title: Co-administration of ondansetron decreases the analgesic efficacy of tramadol in humans.
abstract: Tramadol, a central analgesic acting on serotonin neurotransmission, is often co-used with ondansetron, a 5-HT(3) antagonist, for the management of postoperative pain to decrease nausea and vomiting. The aim of the study is to test the hypothesis that this drug combination raises tramadol requirement by patient-controlled analgesia (PCA). Forty patients undergoing hernioplasty or thyroidectomy were enrolled in a randomized, controlled study and allocated to receive ondansetron 4 mg i.v. (n = 20) or saline (n = 20). At 0, 1, 2, 4 and 24 h of PCA, tramadol consumption was evaluated. Tramadol consumption (mg × kg(-1) × h(-1)) was higher in the ondansetron group at the 2-hour time point compared to the control group (0.24 ± 0.1 vs. 0.17 ± 0.16; p = 0.01). Our study suggests that ondansetron acutely reduces the analgesic efficacy of tramadol.
authors.affiliation: Department of Anaesthesiology, Hospital São Teotónio, Viseu, Portugal.
authors.forename: C
authors.initials: C
authors.lastname: Vale
authors.forename: F
authors.initials: F
authors.lastname: Oliveira
authors.forename: J
authors.initials: J
authors.lastname: Assunção
authors.forename: C
authors.initials: C
authors.lastname: Fontes-Ribeiro
authors.forename: F
authors.initials: F
authors.lastname: Pereira
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016058:Analgesia, Patient-Controlled; D000701:Analgesics, Opioid / Q000008:administration & dosage*; D000932:Antiemetics / Q000008:administration & dosage*; D004311:Double-Blind Method; D004338:Drug Combinations; D004347:Drug Interactions; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017294:Ondansetron / Q000008:administration & dosage*; D010149:Postoperative Pain / Q000188:drug therapy*; D058831:Serotonin 5-HT3 Receptor Antagonists / Q000008:administration & dosage*; D014147:Tramadol / Q000008:administration & dosage*; D014839:Vomiting / Q000139:chemically induced / Q000188:drug therapy; D055815:Young Adult
chemical_list: D000701:Analgesics, Opioid; D000932:Antiemetics; D004338:Drug Combinations; D058831:Serotonin 5-HT3 Receptor Antagonists; D014147:Tramadol; D017294:Ondansetron