ondansetron

on-DAN-se-tron

Therapeutic Classification: antiemetics

Pharmacologic Classification: five ht3 antagonists

REMS

IV: PO: Prevention of nausea and vomiting associated with highly or moderately emetogenic chemotherapy.
Prevention of postoperative nausea and vomiting.
PO: Prevention of nausea and vomiting associated with radiation therapy.

Blocks the effects of serotonin at 5-HT₃ receptor sites (selective antagonist) located in vagal nerve terminals and the chemoreceptor trigger zone in the CNS.

Therapeutic effects:

Decreased incidence and severity of nausea and vomiting following chemotherapy, radiation, or surgery.

Absorption: IV administration results in complete bioavailability; 100% absorbed following oral administration.

Distribution: Unknown.

Metabolism/Excretion: Extensively metabolized by the liver (primarily by CYP3A4); 5% excreted unchanged by the kidneys.

Half-Life: Adults: 3.5–5.5 hr; Children 5 mo–12 yr: 2.9 hr.

(antiemetic effect)

ROUTE	ONSET	PEAK	DURATION
PO, IV	rapid	15–30 min	4–8 hr
IM	rapid	40 min	unknown

Contraindicated in:

Hypersensitivity;
Orally disintegrating tablets contain aspartame and should not be used in patients with phenylketonuria;
Congenital long QT syndrome;
Concurrent use of apomorphine.

Use Cautiously in:

Hepatic impairment;
Abdominal surgery (may mask ileus);
Phenylketonuria (orally disintegrating tablets contain phenylalanine);
OB: Use during pregnancy only if potential maternal benefit justifies potential fetal risk;
Lactation: Safety not established in breastfeeding;
Pedi: Safety and effectiveness not established in children 3 yr (PO) or 1 mo (parenteral).

CV: myocardial ischemia, QT interval prolongation, TORSADES DE POINTES

Derm: STEVENS-JOHNSON SYNDROME, TOXIC EPIDERMAL NECROLYSIS

GI: constipation, diarrhea, ↑liver enzymes, abdominal pain, dry mouth

Neuro: headache, dizziness, drowsiness, extrapyramidal reactions, fatigue, SEROTONIN SYNDROME, weakness

Drug-drug:

Use with apomorphine↑ risk of severe hypotension and loss of consciousness; concurrent use contraindicated.
Carbamazepine, phenytoin, and rifampin may ↓ levels.
Drugs that affect serotonergic neurotransmitter systems, including SSRIs, SNRIs, tricyclic antidepressants, MAOIs, fentanyl, lithium, buspirone, tramadol, methylene blue, and triptans, ↑ risk of serotonin syndrome.

Prevention of Nausea/Vomiting Associated With Highly or Moderately Emetogenic Chemotherapy

PO (Adults ): Highly-emetogenic chemotherapy: 24 mg 30 min prior to chemotherapy.
PO (Adults and Children >11 yr): Moderately emetogenic chemotherapy: 8 mg 30 min prior to chemotherapy and repeated 8 hr later; 8 mg every 12 hr may be given for 1–2 days following chemotherapy.
PO (Children 4–11 yr): Moderately emetogenic chemotherapy: 4 mg 30 min prior to chemotherapy and repeated 4 and 8 hr later; 4 mg every 8 hr may be given for 1–2 days following chemotherapy.
IV (Adults ): 0.15 mg/kg (max dose = 16 mg) 30 min prior to chemotherapy, repeated 4 and 8 hr later.
IV (Children 6 mo–18 yr): 0.15 mg/kg (max dose = 16 mg) 30 min prior to chemotherapy, repeated 4 and 8 hr later.

Hepatic Impairment

PO IM IV (Adults ): Severe hepatic impairment: Not to exceed 8 mg/day.

Prevention of Postoperative Nausea/Vomiting

PO (Adults ): 16 mg 1 hr before induction of anesthesia.
IM IV (Adults and Children >12 yr): 4 mg before induction of anesthesia or postoperatively.
IV (Children 1 mo–12 yr and >40 kg): 4 mg before induction of anesthesia or postoperatively.
IV (Children 1 mo–12 yr and ≤40 kg): 0.1 mg/kg before induction of anesthesia or postoperatively.

Hepatic Impairment

PO IM IV (Adults ): Severe hepatic impairment: Not to exceed 8 mg/day.

Prevention of Nausea/Vomiting Associated With Radiation Therapy

PO (Adults ): 8 mg 1–2 hr prior to radiation; may be repeated every 8 hr, depending on type, location, and extent of radiation.

Hepatic Impairment

PO IM IV (Adults ): Severe hepatic impairment: Not to exceed 8 mg/day.

(Generic available)

Tablets: 4 mg; 8 mg; 24 mg
Orally disintegrating tablets (contain aspartame)strawberry flavor: 4 mg; 8 mg
Oral solutionstrawberry flavor: 4 mg/5 mL
Solution for injection: 2 mg/mL

Assess patient for nausea, vomiting, abdominal distention, and bowel sounds prior to and following administration.
Assess patient for extrapyramidal effects (involuntary movements, facial grimacing, rigidity, shuffling walk, trembling of hands) periodically during therapy.
Monitor ECG in patients with hypokalemia, hypomagnesemia, HF, bradyarrhythmias, or patients taking concomitant medications that prolong the QT interval.
Monitor for signs and symptoms of serotonin syndrome (mental status changes [agitation, hallucinations, delirium, coma], autonomic instability [tachycardia, labile BP, dizziness, diaphoresis, flushing, hyperthermia], neuromuscular symptoms [tremor, rigidity, myoclonus, hyperreflexia, incoordination], seizures, gastrointestinal symptoms [nausea, vomiting, diarrhea]). If symptoms occur, discontinue therapy.
Assess for rash periodically during therapy. May cause Stevens-Johnson syndrome or toxic epidermal necrolysis. Discontinue therapy if severe or if accompanied with fever, general malaise, fatigue, muscle or joint aches, blisters, oral lesions, conjunctivitis, hepatitis, and/or eosinophilia.

Lab Test Considerations:

May cause transient ↑ in serum bilirubin, AST, and ALT levels.

First dose is administered prior to emetogenic event.
PO: For orally disintegrating tablets, do not attempt to push through foil backing; with dry hands, peel back backing and remove tablet. Immediately place tablet on tongue; tablet will dissolve in seconds, then swallow with saliva. Administration of liquid is not necessary.

IV Administration:

Administer undiluted (2 mg/mL) immediately before induction of anesthesia or postoperatively if nausea and vomiting occur shortly after surgery.
Rate: Administer over at least 30 sec and preferably over 2–5 min.
Intermittent Infusion: Diluent: Dilute doses for prevention of nausea and vomiting associated with chemotherapy in 50 mL of D5W, 0.9% NaCl, D5/0.9% NaCl, D5/0.45% NaCl. Solution is clear and colorless. Stable for 7 days at room temperature following dilution.Concentration: 1 mg/mL.
Rate: Administer each dose over 15 min.

Instruct patient to take ondansetron as directed.
Advise patient to notify health care professional immediately if symptoms of irregular heartbeat, serotonin syndrome, or involuntary movement of eyes, face, or limbs occur.
Rep: Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding.

Prevention of nausea and vomiting associated with emetogenic cancer chemotherapy.
Prevention of postoperative nausea and vomiting.
Prevention of nausea and vomiting due to radiation therapy.

~~Zuplenz~~

Ondissolve ODF, Zofran, Zofran ODT

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Assessment ⬆ ⬇

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