Description: Granisetron is a selective serotonin 5-HT3 receptor antagonist. It is a type of antiemetic, a drug used to prevent nausea and vomiting. It is available in various forms, including tablets, oral solutions, and injectable formulations.

Indication: Granisetron is primarily used to prevent nausea and vomiting caused by cancer chemotherapy and radiation therapy. It is also used to prevent and treat postoperative nausea and vomiting.

Mechanism of Action: Chemotherapy and radiation therapy can cause damage to cells in the gastrointestinal tract, which leads to the release of a natural substance called serotonin (5-HT). This serotonin then binds to 5-HT3 receptors located on the vagal nerve terminals in the gut and in the chemoreceptor trigger zone in the brain, which in turn sends signals to the brain’s vomiting center, triggering the vomiting reflex. Granisetron works by selectively and competitively blocking these 5-HT3 receptors. By doing so, it prevents serotonin from binding to them and effectively inhibits the signals that cause nausea and vomiting.