5-HT3 antagonists

5-HT3 antagonist...

1. MECHANISMOF ACTION: Selective 5-HT3 receptor antagonists that act peripherally on vagal nerve endings of the GI tract and centrally in the CTZ. 5-HT3 receptors in the CTZ in the area postrema of the medulla contribute to the perception of nausea and the control of vomiting.

• Post-operative nausea and vomiting (PONV).
• Nausea and vomiting associated with cytotoxic drugs (chemotherapy) and radiotherapy.

• Prolonged QT interval and cardiac conduction defects.
• Hypersensitivity.

• GI disturbance (especially constipation due to increased large bowel transit time).
• Headache.
• Flushing.

• Metabolised predominantly in the liver. t½ for ondansetron and granisetron is ~5 h.

• No specific drug monitoring required.

• Effects reduced by drugs that induce liver enzymes (phenytoin, carbamazepine, rifampicin).
• Increased risk of torsades de pointes with other drugs that prolong the QT interval.

• Establish a cause for emesis prior to prescribing an anti-emetic.
• Very effective anti-emetic agents, particularly for PONV.
• Careful monitoring of symptoms if these drugs are used in patients with subacute bowel obstruction due to effects on large bowel motility.

This note has been edited and reviewed by the pharmacy doctors on NPS team.

• Published on December 20, 2021
• This note last updated in October 30, 2024