Betamethasone does not prevent nausea and vomiting induced by ipecacuanha

Corticosteroids reduce the incidence of PONV but the mode of action is not known. The purpose of this study was to evaluate if betamethasone has serotonin (5-HT) antagonistic effects. Ipecacuanha is known to release serotonin and therefore it was used to induce nausea and vomiting. The 5-HT3 antagonist ondansetron was used as a control substance.

In a randomized, double-blind, cross-over, placebo-controlled study 10 healthy male and female volunteers (6 M/4F), mean age 19.5 (18-23) years, mean weight 69.7 (53-84) kg, were studied on three occasions separated by at least 1 week. They were randomly allocated to receive pretreatment with betamethasone 8 mg, ondansetron 8 mg, or normal saline 2 ml as placebo on each occasion, 15 min before oral ingestion of 30 ml of Ipecacuanha syrup. After ingestion of ipecacuanha, vomitings were recorded and the intensity of nausea was estimated with a visual analog scale during 2 h.

During the first 2 h after ingestion of ipecacuanha nine of the 10 volunteers vomited both after betamethasone and placebo. No volunteer vomited after ondansetron (P < 0.01 vs. betamethasone and placebo). The max VAS for nausea was significantly higher after betamethasone and placebo compared to ondansetron (P < 0.01). There were no statistically significant differences of the max VAS for nausea between betamethasone and placebo.

This study in volunteers has shown that betamethasone does not prevent nausea and vomiting induced by oral intake of ipecacuanha syrup. As ipecacuanha releases 5-hydroxytryptamin, it can be concluded that betamethasone does not have 5-HT3 antagonistic effects.