ONDANSETRON HYDROCHLORIDE

ONDANSETRON HYDROCHLORIDE
(on-dan'si-tron)
Zofran, Zofran ODT
Classifications: antiemetic; 5-ht3 antagonist;
Therapeutic: antiemetic; serotonin (ht3) antagonist

Pregnancy Category: B

Availability

4 mg, 8 mg, 16 mg, 24 mg tablets; 4 mg, 8 mg orally disintegrating tablets; 4 mg/5 mL oral solution; 2 mg/mL, 8 mg/50 mL, 32 mg/50 mL injection

Action

Selective serotonin (5-HT3) receptor antagonist. Serotonin receptors are located centrally in the chemoreceptor trigger zone (CTZ) and peripherally on the vagal nerve terminals. Serotonin is released from the wall of the small intestine and stimulates the vagal efferent nerves through the serotonin receptors and initiates the vomiting reflex.

Therapeutic Effect

Prevents nausea and vomiting associated with cancer chemotherapy and anesthesia.

Uses

Prevention of nausea and vomiting associated with initial and repeated courses of cancer chemotherapy, including high-dose cisplatin; postoperative nausea and vomiting.

Unlabeled Uses

Treatment of hyperemesis gravidarum

Contraindications

Hypersensitivity to ondansetron; children <4 y (PO route).

Cautious Use

Hepatic disease; QT prolongation; PKU; pregnancy (category B), lactation.

Route & Dosage

Prevention of Chemotherapy-Induced Nausea and Vomiting
Adult: PO 8–24 mg 30 min before chemotherapy, then q8h times 2 more doses IV 32 mg or three 0.15 mg/kg doses starting 30 min before chemotherapy, then 4 and 8 h after
Adult/Child (6 mo–18 y): IV 0.15 mg/kg infused over 15 min beginning 30 min before start of chemotherapy, then 4 and 8 h after first dose of ondansetron
Child (>4 y): PO 4 mg 30 min before chemotherapy, then q8h times 2 more doses

Nausea & Vomiting with Highly Emetogenic Chemotherapy
Adult: PO Single 24 mg dose 30 min before administration of single-day highly emetogenic chemotherapy

Postoperative Nausea and Vomiting
Adult: PO 8–16 mg 1 h preoperatively IM/IV 4 mg injected immediately prior to anesthesia induction or once postoperatively if patient experiences nausea/vomiting shortly after surgery
Child: IV 1 mo–12 y, <40 kg, 0.1 mg/kg  1 mo–12 y, >40 kg, 4 mg dose

Hepatic Impairment
Child-Pugh class C: maximum dose 8 mg/d

Administration

Oral
  • Give tablets 30 min prior to chemotherapy and 1–2 h prior to radiation therapy.
  • Do NOT push orally disintegrating tablet through blister foil. Peel foil back and remove tablet. Tablets will disintegrate with/without liquid.
Intravenous

PREPARE: Direct for Post-Op N&V: May be given undiluted.  IV Infusion for Chemo-Induced N&V: Dilute a single does in 50 mL of D5W or NS. May be further diluted in selected IV solution.  

ADMINISTER: Direct: Give over at least 30 sec, 2–5 min preferred.  IV Infusion: Give over 15 min. When three separate doses are administered, infuse each over 15 min.  

INCOMPATIBILITIES Solution/additive: Meropenem. Y-site: Acyclovir, allopurinol, aminophylline, amphotericin B, amphotericin B cholesteryl, ampicillin, ampicillin/sulbactam, amsacrine, cefepime, cefoperazone, fluorouracil, furosemide, ganciclovir, lorazepam, meropenem, methylprednisolone, piperacillin, sargramostim, sodium bicarbonate, TPN.

Adverse Effects (≥1%)

CNS: Dizziness and light-headedness, headache, sedation. GI: Diarrhea, constipation, dry mouth, transient increases in liver aminotransferases and bilirubin. Body as a Whole: Hypersensitivity reactions.

Interactions

Drug: Rifampin may decrease ondansetron levels.

Pharmacokinetics

Peak: 1–1.5 h. Metabolism: In liver (CYP3A4). Elimination: 44–60% in urine within 24 h; 25% in feces. Half-Life: 3 h.

Nursing Implications

Assessment & Drug Effects

  • Monitor fluid and electrolyte status. Diarrhea, which may cause fluid and electrolyte imbalance, is a potential adverse effect of the drug.
  • Monitor cardiovascular status, especially in patients with a history of coronary artery disease. Rare cases of tachycardia and angina have been reported.

Patient & Family Education

  • Be aware that headache requiring an analgesic for relief is a common adverse effect.

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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