Why does oxycodone cause nausea

Ondansetron helps relieve nausea caused by opioids

by Brigitte M. Gensthaler, Munich

Most patients fear nausea and vomiting after tumor therapy and after operations. 5-HT3 antagonists suppress this agony. Ondansetron has also been approved for the prophylaxis and therapy of postoperative emesis since the beginning of the year. Also effective, but not approved, is the classic for opioid-induced vomiting.

The individual risk of a patient suffering from nausea after an operation with inhalation anesthesia can be estimated on the basis of a few parameters: female gender, non-smokers, administration of opioid analgesics and previous experience with travel problems or postoperative nausea. The more criteria are met, the higher the risk. If three or four factors apply, gaseous anesthetics should be avoided, opioids reduced and prophylactic antiemetics given, recommended Professor Dr. Hans-Joachim Schmoll, Director of the Clinic for Hematology and Oncology in Halle at a press conference by GlaxoWellcome in Munich.

Prophylactically, for example, 4 mg of ondansetron (ZofranĀ®) can be injected intravenously when the anesthesia is diverted. The combination with corticosteroids like dexamethasone increases the effectiveness. If the risk is low, prophylaxis is avoided. The antiemetic is only injected when the patient feels discomfort. As in chemotherapy and radiation therapy, the following also applies after operations: Nausea and vomiting must always be treated, as the risk of recurrence is over 50 percent.

According to Schmoll, 10 to 50 percent of patients experience nausea and / or vomiting after taking opioids. Ondansetron helps them too, as two large studies have shown. A double-blind randomized study included 4511 patients who needed an opioid for their pain postoperatively (1). Around 30 percent (1366) had to vomit within six hours and were then given either 8 or 16 mg ondansetron or 10 mg metoclopramide (MCP) intravenously. Both doses of ondansetron suppressed symptoms to the same extent and significantly better than MCP. The metoclopramide patients required additional antiemetic therapy more frequently.

The 5-HT3 antagonist also relieved nausea in non-operated patients who were given opioids for back and neck pain, for example. One fifth (520) of 2574 patients had to undergo antiemetic treatment (2). They received either placebo or ondansetron 8 mg or 16 mg intravenously. The verum suppressed vomiting in 62 to 68 percent, the placebo helped 46 percent of the patients. However, only 15 and 19 percent were free from nausea under verum versus 7 percent under placebo.

Both studies show that ondansetron is more effective at controlling opioid-induced vomiting than either metoclopramide or placebo. It is unclear whether this can also be achieved with lower doses.

literature

(1) Chung, F., et al., Ondansetron is more effective than metoclopramide for the treatment of opioid-induced emesis in post-surgical adult patients. Eur. J. Anaestesiol. 16 (1999) 669-677.
(2) Sussman, G., et al., Intravenous Ondansetron for the Control of Opioid-Induced Nausea and Vomiting. Clin. Therapeutics Vol. 21 (1999) 1216-1227.

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