granisetron

Granisetron is a selective antiemetic in the class of 5-HT3 receptor antagonists. It blocks serotonin 5-HT3 receptors both in the peripheral nervous system of the gut and in the central nervous system, particularly the chemoreceptor trigger zone, to reduce nausea and vomiting.

Indications include prevention of chemotherapy-induced nausea and vomiting (CINV), radiotherapy-induced emesis, and postoperative nausea and vomiting (PONV). Granisetron is available in several formulations, including oral tablets, intravenous injections, and a transdermal patch, providing alternatives for different clinical needs and patient preferences.

Administration and dosing vary by formulation and indication. In adults, intraveneous doses around 1 mg before chemotherapy and oral doses around 1–2 mg are commonly used, with pediatric regimens adjusted by weight and clinical judgment. The transdermal patch offers prolonged antiemetic coverage. Dosing should follow product labeling and clinician guidance.

Pharmacokinetics and metabolism: granisetron is metabolized in the liver and excreted via the urine and feces. It has a systemic presence of several hours, with the precise duration depending on formulation and patient factors such as hepatic function.

Adverse effects are generally modest and may include headache, constipation, and dizziness. There is a risk of QT interval prolongation and rare cardiac arrhythmias, particularly in patients with preexisting QT prolongation, electrolyte disturbances, or concomitant QT-prolonging drugs. Hypersensitivity reactions are uncommon but possible.

Contraindications include known hypersensitivity to granisetron or other 5-HT3 antagonists. Caution is advised in patients with hepatic impairment, electrolyte disturbances, or concurrent medications that affect cardiac repolarization.