Effects of Ondansetron and Granisetron on Rocuronium-induced Neuromuscular Blockade in a Rat Phrenic Nerve-hemidiaphragm Preparation

Background: Both ondansetron and granisetron exert their antiemetic effects via a blockade of the 5-hydroxytryptamine 3 receptor (). Because the is a member of a superfamily of ligand-gated ion channels and has structural similarities to the nicotinic acetylcholine receptor (nAChR), a antagonist may also inhibit the nAChR. This study examined the effects of antagonists, ondansetron and granisetron, on rocuronium-induced neuromuscular blockade in vitro. Methods: Rat phrenic nerve-hemidiaphragm preparations were isolated and allocated randomly into seven groups (control, 1, 10, 100/ml of ondansetron, 0.1, 1, 10/ml of granisetron). Two studies were carried out using single twitch responses. In the cumulative dose-response study, rocuronium 1/ml and each doses of ondansetron or granisetron were administered simultaneously, and incremental 0.5/ml doses of rocuronium were added to obtain more than 95% neuromuscular twitch inhibition. , , , and of rocuronium in each group were calculated using a logistic model. In the partial curarization study, the twitch heights were measured after administering ondansetron or granisetron (10 minutes after administering 3/ml rocuronium) and were measured 10 minutes later. The 2 twitch heights were then compared. Results: In the cumulative dose-response study, ondansetron 100/ml and granisetron 10/ml significantly reduced the of rocuronium (P ＜ 0.05). There were no intergroup differences in the partial curarization study. Conclusions: High concentration of ondansetron and granisetron enhanced the neuromuscular blockade of rocuronium. Granisetron enhanced the neuromuscular blockade of rocuronium more potently than ondansetron.