Interactions between granisetron-hydrochloride(granisetron) and Chem mart tramadol (traMADOL)
granisetron and traMADOL (Moderate Drug-Drug)
MONITOR: Concurrent use of 5-HT3 receptor antagonists may reduce the analgesic efficacy of tramadol. The proposed mechanism is antagonism of serotonin-mediated effects of tramadol at the spinal level. In a randomized, double-blind study of 40 patients undergoing lumbar laminectomy, patients who were administered ondansetron 4 mg at induction of anesthesia required more tramadol postsurgery than control patients who had been given saline. Cumulative tramadol use via a PCA pump was 26% to 35% higher in the ondansetron group the first 4 hours postoperatively and 22% to 25% higher thereafter. Tramadol use on an hourly basis did not differ significantly between the two groups except in the first postoperative hour, probably because of the relatively short plasma half-life of ondansetron. The 4 mg dose of ondansetron did not reduce the 24-hour incidence of postoperative nausea and vomiting.
MANAGEMENT: No particular intervention is required. However, the possibility of a diminished therapeutic response to tramadol should be considered during concomitant therapy with 5-HT3 receptor antagonists.
