Ondansetron

Ondansetron

Drug monograph · NCLEX study reference
Trade names	Zofran
Therapeutic class	Antiemetic
Pharmacologic class	Serotonin 5-HT3 receptor antagonist
Onset / peak / duration	Onset within 30 minutes; duration about 8 hours.
Half-life / level	Half-life about 3 to 6 hours; no routine level.
Routes	PO (oral), IV
High-alert (ISMP)	No
Black box warning	None
Antidote / reversal	Supportive care.
Pregnancy / lactation	Used when needed; weigh risks.

Nursing pharmacology study reference (NCLEX-style monograph). Numeric values are standard teaching ranges for study and must be verified against current manufacturer labeling before clinical use. This is educational content, not prescribing guidance.

Ondansetron (brand name Zofran) — Antiemetic; Serotonin 5-HT3 receptor antagonist.

Identification

• Therapeutic class: Antiemetic.
• Pharmacologic class: Serotonin 5-HT3 receptor antagonist.

Pharmacology

• Mechanism of action: Blocks serotonin 5-HT3 receptors centrally and in the gut to prevent nausea and vomiting.
• Onset / peak / duration: Onset within 30 minutes; duration about 8 hours.
• Half-life / therapeutic level: Half-life about 3 to 6 hours; no routine level.

Clinical use

• Indications: Chemotherapy, postoperative, and other nausea and vomiting.
• Usual dose, route, frequency: 4 to 8 mg PO, ODT, or IV every 8 hours as needed.
• Maximum dose / adjustments: Single IV doses limited (often 16 mg) for QT safety; reduce in severe hepatic impairment.

Safety

• Contraindications: Use with apomorphine, congenital long QT.
• Black box warning: None.
• Interactions: QT-prolonging drugs, serotonergic drugs (serotonin syndrome), apomorphine (profound hypotension).
• Pregnancy / lactation: Used when needed; weigh risks.
• High-alert: No.

Adverse effects

• Common side effects: Headache, constipation, fatigue.
• Serious effects to report: QT prolongation, serotonin syndrome.
• Antidote / reversal: Supportive care.

Nursing process

• Assessment before administration: Nausea, ECG and electrolytes if QT risk.
• Interventions during therapy: Give before chemotherapy; push IV slowly.
• Monitor: Nausea relief, QT in at-risk patients, electrolytes.
• Evaluation / expected outcome: Reduced nausea and vomiting.

Patient teaching

• Patient teaching: ODT placed on the tongue; report palpitations.
• Notify provider if: Palpitations, fainting, agitation with fever.
• Administration tips: ODT on tongue; IV given slowly.