Nurses Compass
Drug Guide
Granisetron Hydrochloride
Classification
Therapeutic: Antiemetic
Pharmacological: Serotonin 5-HT3 receptor antagonist
FDA Approved Indications
- Prevention of chemotherapy-induced nausea and vomiting (CINV)
- Prevention of radiation therapy-induced nausea and vomiting
Mechanism of Action
Granisetron selectively antagonizes serotonin (5-HT3) receptors both centrally in the chemoreceptor trigger zone and peripherally on vagal nerve terminals in the gastrointestinal tract, thereby blocking the vomiting reflex pathway.
Dosage and Administration
Adult: Typically 1 mg administered intravenously 30 minutes prior to chemotherapy or radiation; can be repeated every 8 hours as needed, up to a total of 2 mg per day.
Pediatric: Dosage varies based on age and weight; usually 10 mcg/kg IV administered 30 minutes prior to chemotherapy, with additional doses as needed.
Geriatric: No specific dosage adjustment is usually required; monitor for increased sensitivity.
Renal Impairment: No dose adjustment necessary for mild to moderate impairment; severe impairment requires cautious use.
Hepatic Impairment: No specific adjustment recommended.
Pharmacokinetics
Absorption: Rapidly absorbed after oral administration; bioavailability approximately 60%.
Distribution: Widely distributed, crosses the blood-brain barrier.
Metabolism: Metabolized primarily in the liver via oxidation by cytochrome P450 enzymes.
Excretion: Excreted mainly in urine (approximately 74%), with some fecal excretion.
Half Life: Approximately 2-4 hours.
Contraindications
- Known hypersensitivity to granisetron or other 5-HT3 receptor antagonists.
Precautions
- Use cautiously in patients with prior history of arrhythmias or those taking medications that prolong QT interval.
- Report any signs of hypersensitivity or adverse reactions promptly.
- Pregnancy category B; should be used during pregnancy only if clearly needed.
- Lactation: Because of potential for adverse effects, use with caution.
Adverse Reactions - Common
- Headache (Common)
- Constipation (Common)
- Dizziness (Common)
Adverse Reactions - Serious
- QT prolongation, Torsades de Pointes (Rare)
- Serious hypersensitivity reactions (Rare)
Drug-Drug Interactions
- Medications prolonging QT interval (e.g., amiodarone, sotalol)
- Other serotonergic drugs which may increase risk of serotonin syndrome
Drug-Food Interactions
N/ADrug-Herb Interactions
N/ANursing Implications
Assessment: Monitor for efficacy in controlling nausea/vomiting; observe cardiac status, especially QT interval if on other QT-prolonging drugs.
Diagnoses:
- Risk for electrolyte imbalance due to vomiting
- Risk for arrhythmias
Implementation: Administer per prescription, preferably 30 minutes before chemotherapy or radiation;
Evaluation: Assess patient's nausea/vomiting control and monitor for adverse effects.
Patient/Family Teaching
- Take medication exactly as prescribed.
- Report any abnormal heartbeat, dizziness, or fainting.
- Notify healthcare provider if you experience headache or constipation.
- Avoid use of other serotonergic medications unless directed by healthcare provider.
Special Considerations
Black Box Warnings:
- QT prolongation and arrhythmia risk
Genetic Factors: None specifically identified.
Lab Test Interference: None noted.
Overdose Management
Signs/Symptoms: Severe bradycardia, hypotension, arrhythmias, CNS disturbances.
Treatment: Supportive care; monitor cardiac function; activated charcoal may be considered if ingestion is recent.
Storage and Handling
Storage: Store at 20-25°C (68-77°F), protected from light and moisture.
Stability: Stable under recommended storage conditions; discard expired medications.