granisetron hydrochloride

Action

Binds to serotonin receptors in chemoreceptor trigger zone and vagal nerve terminals, blocking serotonin release and controlling nausea and vomiting

Availability

Injection: 1 mg/ml

Oral solution: 2 mg/10 ml in 30-ml bottles

Tablets: 1 mg

Transdermal system (patch): 52-cm² patch (containing 34.3 mg granisetron delivering 3.1 mg/24 hours)

Indications and dosages

➣ To prevent nausea and vomiting caused by chemotherapy

Adults and children ages 2 to 16: For I.V. use, 10 mcg/kg I.V. within 30 minutes before chemotherapy. For P.O. use (adults only), 1 mg P.O. b.i.d., with first dose given at least 1 hour before chemotherapy and second dose given 12 hours later on days when chemotherapy is administered; or 2 mg P.O. daily at least 1 hour before chemotherapy. For transdermal use (adults only), apply patch for up to 7 days.

➣ To prevent nausea and vomiting caused by radiation therapy

Adults: 2 mg P.O. daily within 1 hour of radiation therapy

➣ Acute postoperative nausea and vomiting

Adults: 1 mg I.V. undiluted, administered over 30 seconds

Contraindications

• Hypersensitivity to drug

Precautions

Use cautiously in:

• pregnant or breastfeeding patients

• children younger than age 18 (safety of P.O. and transdermal use not established)

• children younger than age 2 (safety of I.V. use not established).

Administration

• For I.V. infusion, dilute with 20 to 50 ml of normal saline solution or dextrose 5% in water.

• Infuse I.V. over 5 minutes, starting 30 minutes before chemotherapy.

• For direct I.V. injection, give undiluted over 30 seconds.

• Don't mix I.V. form with other drugs.

• For P.O. use, give first dose 1 hour before chemotherapy and second dose 12 hours after first.

• Apply a single transdermal patch to upper outer arm for 24 to 48 hours before chemotherapy.

• Remove patch a minimum of 24 hours after chemotherapy completion. Patch may be worn up to 7 days depending on duration of chemotherapy.

Adverse reactions

CNS: headache, anxiety, stimulation, weakness, drowsiness, dizziness

CV: hypertension

GI: nausea, vomiting, diarrhea, constipation, abdominal pain

Hematologic: anemia, leukopenia, thrombocytopenia

Skin: alopecia, application site reactions (patch)

Other: altered taste, decreased appetite, fever, chills, shivering

Interactions

Drug-diagnostic tests. Alanine aminotransferase, aspartate aminotransferase: increased levels

Electrolytes: altered levels

Hemoglobin, platelets, white blood cells: decreased levels

Drug-herbs. Horehound: enhanced serotonergic effects

Patient monitoring

• Monitor hepatic enzyme levels and CBC with white cell differential.

• Monitor temperature and blood pressure. Have patient use caution when ambulating, to avoid orthostatic hypotension.

• Know that patch may be degraded by direct exposure to natural or artificial sunlight.

Patient teaching

• Instruct patient to apply a single transdermal patch to upper outer arm 24 to 48 hours before chemotherapy.

• Instruct patient to remove patch by gently peeling it off in a minimum of 24 hours after chemotherapy completion.

• Instruct patient to remove patch if a severe or generalized skin reaction (such as rash or itching) occurs.

• Advise patient to avoid direct exposure of application site to natural or artificial sunlight by covering site with clothing while wearing patch and for 10 days after patch removal.

• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.

• Advise patient to minimize GI upset by eating frequent, small servings of healthy food.

• Tell patient he'll undergo regular blood testing during therapy.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the tests and herbs mentioned above.