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Drugs, Supplies and Delivery
Palonosetron
Palonosetron is a second-generation selective serotonin 5-HT3 receptor antagonist used to prevent and treat nausea and vomiting caused by chemotherapy and surgery. It is particularly effective in managing acute and delayed chemotherapy-induced nausea and vomiting (CINV) due to its long half-life and high receptor-binding affinity. 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 palonosetron, including its mechanism, uses, dosing, side effects, precautions, and drug interactions.
Palonosetron works by selectively blocking 5-HT3 receptors in the chemoreceptor trigger zone (CTZ) and the gastrointestinal (GI) tract. By inhibiting these receptors, palonosetron:
- 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).
Palonosetron has a long half-life (40 hours) and a high affinity for 5-HT3 receptors, making it effective for both acute and delayed CINV (BNF).
- Chemotherapy-Induced Nausea and Vomiting (CINV):
- Used to prevent acute and delayed nausea and vomiting associated with moderately to highly emetogenic chemotherapy (BNF).
- Postoperative Nausea and Vomiting (PONV):
- Effective in preventing nausea and vomiting after surgery (Lippincott).
- Chemotherapy-Induced Nausea and Vomiting:
- 0.25 mg intravenously 30 minutes before chemotherapy (BNF).
- 0.5 mg orally 1 hour before chemotherapy (Lippincott).
- Postoperative Nausea and Vomiting:
- 0.075 mg intravenously immediately before induction of anesthesia (Lange).
Administration:
- Intravenous doses should be administered slowly over 30 seconds to minimize side effects.
- Oral capsules should be taken with or without food (BNF).
- 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: Palonosetron may reduce the analgesic effect of tramadol (Lange).
Palonosetron is the generic name for this medication. It is marketed under the brand name Aloxi®. Generic versions are also available, making it more accessible for patients.
