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Drugs, Supplies and Delivery
Granisetron
Granisetron is a selective serotonin 5-HT3 receptor antagonist used to prevent and treat nausea and vomiting caused by chemotherapy, radiotherapy, and surgery. It is particularly effective in managing chemotherapy-induced nausea and vomiting (CINV) and is available in oral, intravenous, and transdermal formulations. This article synthesizes information from the British National Formulary (BNF), Lippincott Textbook of Pharmacology, and Lange Basic & Clinical Pharmacology to provide a detailed overview of granisetron, including its mechanism, uses, dosing, side effects, precautions, and drug interactions.
Granisetron works by selectively blocking 5-HT3 receptors in the chemoreceptor trigger zone (CTZ) and the gastrointestinal (GI) tract. By inhibiting these receptors, granisetron:
- Prevents the stimulation of the vomiting center in the brain, reducing nausea and vomiting.
- Blocks serotonin release from enterochromaffin cells in the GI tract, which is often triggered by chemotherapy or radiation (Lippincott, Lange).
Granisetron’s high selectivity for 5-HT3 receptors minimizes its effects on other receptor systems, reducing the risk of side effects like sedation or extrapyramidal symptoms (BNF).
- Chemotherapy-Induced Nausea and Vomiting (CINV):
- Used to prevent acute and delayed nausea and vomiting associated with highly emetogenic chemotherapy (BNF).
- Radiotherapy-Induced Nausea and Vomiting:
- Effective in managing nausea and vomiting caused by radiation therapy (Lippincott).
- Postoperative Nausea and Vomiting (PONV):
- Used to prevent and treat nausea and vomiting after surgery (Lange).
- Chemotherapy-Induced Nausea and Vomiting:
- 1–2 mg orally 1 hour before chemotherapy, or 1 mg intravenously 30 minutes before chemotherapy (BNF).
- Transdermal patch: 3.1 mg/24 hours, applied 24–48 hours before chemotherapy and left on for up to 7 days (Lippincott).
- Radiotherapy-Induced Nausea and Vomiting:
- 2 mg orally once daily, starting 1 hour before radiotherapy (Lange).
- Postoperative Nausea and Vomiting:
- 1 mg intravenously before or after surgery (BNF).
Administration:
- Oral tablets can be taken with or without food.
- Intravenous administration should be done slowly over 30 seconds to 5 minutes to avoid side effects (Lippincott).
- Transdermal patches should be applied to clean, dry, intact skin on the upper arm (Lange).
- Common: Headache, constipation, and dizziness (Lippincott).
- Serious:
- QT Prolongation: Risk of arrhythmias, particularly with high doses or in patients with underlying heart conditions (Lange).
- Hypersensitivity Reactions: Rare cases of anaphylaxis or rash (BNF).
- QT Prolongation: Avoid in patients with congenital long QT syndrome or those taking other QT-prolonging drugs (BNF).
- Pregnancy: Generally considered safe but should be used under medical supervision (Lippincott).
- Liver Impairment: Dose adjustment is not typically required, but caution is advised in severe hepatic impairment (Lange).
- QT-Prolonging Drugs (e.g., amiodarone, sotalol): Increased risk of arrhythmias (BNF).
- Apomorphine: Contraindicated due to risk of profound hypotension and loss of consciousness (Lippincott).
- Tramadol: Granisetron may reduce the analgesic effect of tramadol (Lange).
Granisetron is the generic name for this medication. It is marketed under the brand name Kytril® (oral and IV formulations) and Sancuso® (transdermal patch). Generic versions are widely available and cost-effective.
