Ondansetron
Generic Details
Generic Name
Ondansetron
Other Names
- Zofran
- Zuplenz
- Ondisolv
Drug Class
- Serotonin 5-HT3 receptor antagonist
- Antiemetic
Chemical Formula
C18H19N3O
Molecular Weight
293.36 g/mol
Mechanism of Action
- Blocks the serotonin 5-HT3 receptors peripherally on vagal nerve terminals and centrally in the chemoreceptor trigger zone.
Indications
- Nausea and vomiting caused by chemotherapy
- Nausea and vomiting after surgery
- Radiation-induced nausea and vomiting
Common Dosage Forms
- Tablet
- Orally disintegrating tablet
- Oral solution
- Injectable solution
Typical Dosage
- 8 mg orally 3 times a day
- 16 mg orally 1 hour before chemotherapy
- 0.15 mg/kg intravenously 30 minutes before chemotherapy
Pediatric Dosage
- 0.15 mg/kg orally 3 times a day
- 8 mg orally 1 to 2 hours before chemotherapy
Geriatric Dosage
- No adjustment required
Side Effects
- Headache
- Constipation
- Fatigue
- Dizziness
- Diarrhea
Contraindications
- Hypersensitivity to ondansetron or any component of the formulation
Pregnancy Category
- Category B - No evidence of risk in humans
Lactation Safety
- Excretion in breast milk is unknown; use caution
Drug Interactions
- Apomorphine
- Tramadol
- Lithium
- Phenytoin
Overdose Symptoms
- Blurred vision
- Severe constipation
- Loss of coordination
Antidote for Overdose
- There is no specific antidote; management is symptomatic and supportive
Storage Conditions
- Store at room temperature away from moisture and heat
Pharmacokinetics
- Absorption: Rapidly absorbed after oral administration
- Distribution: Crosses the placenta and enters breast milk
- Metabolism: Metabolized in the liver
- Excretion: Eliminated in urine (70-85%) and feces (12%)
Precautions
- Patients with a history of cardiac conduction abnormalities
- Patients with electrolyte abnormalities
Warnings
- May increase the risk of serotonin syndrome when combined with other serotonergic drugs
Others
- May be used in the management of hyperemesis gravidarum