Nurses Compass
Drug Guide
Granisetron
Classification
Therapeutic: Anti-nausea and antiemetic
Pharmacological: 5-HT3 receptor antagonist
FDA Approved Indications
- Prevention of nausea and vomiting associated with chemotherapy and radiotherapy
Mechanism of Action
Granisetron works by selectively blocking serotonin 5-HT3 receptors in the central and peripheral nervous systems, thereby reducing nausea and vomiting signals.
Dosage and Administration
Adult: Sancuso: Transdermal patch applied once weekly, typically 3 hours before chemotherapy. Sustol: Subcutaneous injection usually 2 mg 30 minutes before chemotherapy.
Pediatric: Use and dosing in pediatric patients are not well established; consult specialized guidelines.
Geriatric: Adjustments generally not required but monitor for increased sensitivity.
Renal Impairment: No specific adjustment required.
Hepatic Impairment: Use with caution; no specific dose adjustment established.
Pharmacokinetics
Absorption: Rapid absorption following transdermal application (Sancuso) and subcutaneous injection (Sustol).
Distribution: Widely distributed, crosses the blood-brain barrier.
Metabolism: Metabolized primarily in the liver via CYP3A4, CYP1A2, and CYP2D6.
Excretion: Excreted mainly in urine and feces.
Half Life: Approximately 8 hours (oral and IV forms); transdermal provides sustained release over 7 days.
Contraindications
- Known hypersensitivity to granisetron or other 5-HT3 receptor antagonists.
Precautions
- Use with caution in patients with a history of arrhythmias, QT prolongation, or concomitant QT-prolonging drugs.
Adverse Reactions - Common
- Headache (Common)
- Constipation (Common)
- Mild dizziness (Common)
Adverse Reactions - Serious
- QT prolongation leading to arrhythmias (e.g., Torsades de Pointes) (Rare)
- Serotonin syndrome (when combined with other serotonergic drugs) (Rare)
Drug-Drug Interactions
- Caution with other QT-prolonging agents (e.g., certain antidepressants, antiarrhythmics).
Drug-Food Interactions
N/ADrug-Herb Interactions
N/ANursing Implications
Assessment: Assess for baseline cardiac status, especially QT interval before administration.
Diagnoses:
- Risk of cardiac dysrhythmias
Implementation: Administer as per prescribed route; monitor ECG if indicated; observe for signs of arrhythmias.
Evaluation: Evaluate for reduction in nausea and vomiting; monitor for adverse effects.
Patient/Family Teaching
- Report any signs of arrhythmias (palpitations, dizziness, fainting).
- Follow application instructions for transdermal patches.
- Avoid other QT-prolonging drugs without medical advice.
Special Considerations
Black Box Warnings:
- QT prolongation and serious arrhythmias are rare but serious.
Genetic Factors: No specific genetic factors impacting use but consider pharmacogenetic testing for CYP3A4 metabolized drugs if relevant.
Lab Test Interference: None noted.
Overdose Management
Signs/Symptoms: Serious CNS effects such as agitation, confusion, hallucinations; potential arrhythmias.
Treatment: Supportive care; manage symptoms; correct arrhythmias; activated charcoal if ingestion is recent.
Storage and Handling
Storage: Store at room temperature away from light and moisture.
Stability: Stable for the duration of the recommended shelf life.