Granisetron is a serotonin 5-HT3 receptor antagonist used as an antiemetic to treat nausea and vomiting following chemotherapy. Its main effect is to reduce the activity of the vagus nerve, which is a nerve that activates the vomiting center in the medulla oblongata. It does not have much effect on vomiting due to motion sickness. This drug does not have any effect on dopamine receptors or muscarinic receptors. Granisetron is metabolized slowly by the liver, giving it a longer than average half-life. One dose usually lasts 4 to 9 hours and is usually administered once or twice daily. This drug is removed from the body by the liver and kidneys. A number of medications including granisetron appear to be effective in controlling post-operative nausea and vomiting (PONV). It is unclear if it is better than or worse than other agents like droperidol, metoclopramide, ondansetron or cyclizine.
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