Granisetron HCl

A to Z Drug Facts

 Action Selective 5-HT₃ receptor antagonists. Serotonin receptors of the 5-HT₃ type are located peripherally on vagal nerve terminals, enteric neurons in the GI tract, and centrally in the chemoreceptor trigger zone. During chemotherapy, mucosal enterochromaffin cells from the small intestine release serotonin, which stimulates the 5-HT₃ receptors. This evokes vagal afferent discharge, inducing vomiting. Clearance is predominantly by hepatic metabolism, and plasma protein binding is approximately 65%.

 Indications

Adult: Prevention of chemotherapy-induced nausea and vomiting; prevention of radiation-induced nausea and vomiting (oral only); postoperative nausea and vomiting (injection only).

Pediatric (2 to 16 yr): Prevention of chemotherapy-induced nausea and vomiting (injection only). Safety and efficacy not established in patients younger than 2 yr.

 Contraindications Standard considerations.

 Route/Dosage

Chemotherapy-Induced Nausea and Vomiting

Adults: IV 10 mcg/kg (commonly rounded to nearest 1 mg), given up to 30 min before starting chemotherapy. Give only on day(s) of chemotherapy.

Chemotherapy-Induced Nausea and Vomiting

Adults: PO 1 mg bid. Give the first oral dose up to 1 hr before chemotherapy and the second dose 12 hr later. Give granisetron only on day(s) of chemotherapy. Alternately, a single 2 mg dose may be given up to 1 hr before chemotherapy. Pediatric: IV 10 mcg/kg, given up to 30 min before starting chemotherapy. Give only on day(s) of chemotherapy.

Radiation-Induced Nausea and Vomiting

Adults: PO 2 mg once daily. Give the dose up to 1 hr before radiation therapy. Give granisetron only on day(s) of radiation therapy.

Prevention/Treatment Postoperative Nausea and Vomiting

Adults: IV Prevention: 1 mg undiluted, administered over 30 seconds, before induction of anesthesia or immediately before reversal of anesthesia. Treatment: 1 mg undiluted, administered over 30 seconds, after surgery.

 Interactions

Cytochrome P450 enzymes: Granisetron does not induce or inhibit the cytochrome P450 system; however, it is metabolized partially by cytochrome P450 3A enzymes. Medications that induce or inhibit cytochrome P450 3A isoenzymes may alter granisetron metabolism.

 Lab Test Interferences None well documented.

 Adverse Reactions

CARDIOVASCULAR: Hypertension; hypotension. CNS: Headache; somnolence; agitation; anxiety; mood changes; insomnia. DERMATOLOGIC: Rash. GI: Constipation; diarrhea; elevated AST and ALT; decreased appetite. MUSCULOSKELETAL: Asthenia. OTHER: Fever; taste disorder; shivers; alopecia.

 Precautions

Pregnancy: Category B. Lactation: Undetermined. Children: Safety and efficacy of the injection in children younger than 2 yr not established. Delayed nausea and vomiting: Granisetron is not consistently effective for treating delayed nausea and vomiting.

 Administration/Storage

• All dosage forms can be stored at room temperature or refrigerated. Protect granisetron injection from light.
• Diluted granisetron for injection is stable up to 3 days refrigerated or up to 7 days at room temperature under normal lighting conditions.
• Administer by oral, IV push, or IV infusion.
• Undiluted granisetron may be given IV over 30 sec.
• Diluted granisetron solutions are infused over 5 min. Infuse admixtures containing granisetron and dexamethasone over 15 to 30 min.
• Oral solution and tablets are interchangeable.

Extemporaneous oral suspension

• Granisetron 1 mg/5 mL oral suspension: Crush twelve 1 mg oral tablets completely and suspend in 30 mL of distilled water. Dilute with sufficient cherry syrup for a final total volume of 60 mL.
• The extemporaneous suspension is stable for up to 14 days when stored in amber plastic bottles.

IV

• Dilute with 0.9% Sodium Chloride or 5% Dextrose to a total volume of 20 to 50 mL.

 Assessment/Interventions

• Obtain patient history, including drug history, and any known allergies. Note history of prior use and effectiveness of antiemetic therapy.
• Monitor patient for antiemetic efficacy. Notify health care provider if nausea or vomiting are not prevented.
• Monitor patient for CNS, GI, and general body side effects. Inform health care provider if noted and significant.

 Patient/Family Education

• Explain name, dose, action, and potential side effects of drug.
• Advise patient, family, or caregiver that IV medication will be prepared and administered by health care professional in a medical facility.
• Review dosing schedule with patient. Caution patient taking oral medication that tablets or solution must be taken no more than 1 hr before chemotherapy administration or radiation therapy to provide greatest protection against nausea and vomiting.
• Advise patient that medication will greatly reduce likelihood of nausea or vomiting but these are still possible.
• Instruct patient to inform health care provider if medication does not prevent nausea or vomiting.
• Advise patient to report any of the following to their health care provider: intolerable headache; persistent or intolerable constipation or diarrhea; persistent weakness.
• Instruct women to notify health care provider if pregnant, planning to become pregnant, or breastfeeding.
• Instruct patient to not take any prescription or OTC medications or dietary supplements unless advised by health care provider.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts