GRANISETRON

GRANISETRON
(gran'i-se-tron)
Kytril
Classifications: antiemetic; 5-ht₃ antagonist;
Therapeutic: antiemetic; 5-ht₃ antagonist
Prototype: Ondansetron
Pregnancy Category: B

Availability

1 mg tablets; 1 mg/mL injection

Action

Granisetron is a selective serotonin (5-HT₃) receptor antagonist. Serotonin receptors of the 5-HT₃ type are located centrally in the chemoreceptor trigger zone, and peripherally on the vagal nerve terminals. Serotonin released from the wall of the small intestine stimulates the vagal afferent neurons through the serotonin (5-HT₃) receptors, and initiates the vomiting reflex.

Therapeutic Effect

This selective serotonin (5-HT₃) receptor antagonist is used for the prevention of nausea and vomiting associated with cancer chemotherapy.

Uses

Prevention of nausea and vomiting associated with initial and repeat courses of emetogenic cancer therapy, including high-dose cisplatin, postoperative nausea and vomiting.

Contraindications

Hypersensitivity to granisetron, or benzyl alcohol; GI obstruction; neonates; children less than 2 y.

Cautious Use

Hypersensitivity to ondansetron or similar drugs; liver disease, pregnancy (category B), lactation.

Route & Dosage

Chemotherapy-Related Nausea and Vomiting
Adult/Child: IV >2 y, 10 mcg/kg, beginning at least 30 min before initiation of chemotherapy (up to 40 mcg/kg per dose has been used) PO 1 mg b.i.d., start 1 mg up to 1 h prior to chemotherapy, then second tab 12 h later OR 2 mg q.d.

Postoperative Nausea and Vomiting
Adult: IV 1 mg before anesthesia induction or before reversal of anesthesia

Administration

Oral

Give only on the day of chemotherapy.

Intravenous

PREPARE: Direct: Give undiluted. IV Infusion: Dilute in NS or D5W to a total volume of 20–50 mL. Prepare infusion at time of administration; do not mix in solution with other drugs.

ADMINISTER: Direct: Give a single dose over 30 sec. IV Infusion: Infuse diluted drug over 5 min or longer; complete infusion 20–30 min prior to initiation of chemotherapy.

INCOMPATIBILITIES Y-site: Amphotericin B, doxorubicin.

Store at 15°–30° C (59°–86° F) for 24 h after dilution under normal lighting conditions.

Adverse Effects (≥1%)

CNS: Headache, dizziness, somnolence, insomnia, labile mood, anxiety, fatigue. GI: Constipation, diarrhea, elevated liver function tests.

Interactions

Drug: Ketoconazole may inhibit metabolism.

Pharmacokinetics

Onset: Several minutes. Duration: Approximately 24 h. Distribution: Widely distributed in body tissues. Metabolism: Appears to be metabolized in liver. Elimination: Excreted in urine as metabolites. Half-Life: 10–11 h in cancer patients, 4–5 h in healthy volunteers.

Nursing Implications

Assessment & Drug Effects

Monitor the frequency and severity of nausea and vomiting.
Lab tests: Monitor liver function; elevated AST and ALT values usually normalize within 2 wk of last dose.
Assess for headache, which usually responds to nonnarcotic analgesics.

Patient & Family Education

Note: Headache requiring an analgesic for relief is a common adverse effect.
Learn ways to manage constipation.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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