ZOFRAN PRESERVATIVE FREE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ZOFRAN PRESERVATIVE FREE (ZOFRAN PRESERVATIVE FREE).
Selective 5-HT3 receptor antagonist; blocks serotonin binding at 5-HT3 receptors in the chemoreceptor trigger zone (CTZ) and gastrointestinal tract, inhibiting emetic reflex.
| Metabolism | Hepatic metabolism via CYP1A2, CYP2D6, and CYP3A4; minor contribution from flavin-containing monooxygenase (FMO). |
| Excretion | Approximately 5% of ondansetron is excreted unchanged in urine; the remainder is extensively metabolized, with metabolites excreted in urine (46-60%) and feces (22-29%). |
| Half-life | Terminal elimination half-life is approximately 3-6 hours in adults, but may be prolonged to 15-20 hours in severe hepatic impairment (Child-Pugh class C). |
| Protein binding | 70-76% bound to plasma proteins. |
| Volume of Distribution | Vd approximately 1.9-2.5 L/kg, indicating extensive extravascular distribution. |
| Bioavailability | Oral bioavailability is approximately 60% due to first-pass metabolism; bioavailability is not applicable for IV and IM routes (100%). |
| Onset of Action | Intravenous: within 1-2 minutes; oral: within 30-60 minutes; intramuscular: within 10-20 minutes; orally disintegrating tablet: within 30-60 minutes. |
| Duration of Action | Duration of antiemetic effect is 4-8 hours after IV administration; up to 6-12 hours after oral administration; may be prolonged with hepatic impairment. |
| Molecular Weight | 365.9 |
4-8 mg intravenously or intramuscularly as a single dose for prevention of chemotherapy-induced nausea and vomiting; 8 mg orally 30 minutes before chemotherapy, repeated every 8-12 hours as needed.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for GFR >30 mL/min; for GFR ≤30 mL/min, dosing interval should be extended to every 24 hours. |
| Liver impairment | Severe hepatic impairment (Child-Pugh C): maximum daily dose of 8 mg; moderate impairment (Child-Pugh B): no dose adjustment recommended; mild impairment (Child-Pugh A): no adjustment. |
| Pediatric use | For chemotherapy-induced nausea and vomiting: intravenous dose of 0.15 mg/kg per dose (maximum 8 mg) given 30 minutes before chemotherapy, repeated every 4 hours; orally: 4 mg for children ≤30 kg, 8 mg for children >30 kg, given 30 minutes before chemotherapy. |
| Geriatric use | No specific dose adjustment required; however, due to potential reduced renal function, consider monitoring and possible interval extension as per renal adjustment guidelines. |
| 1st trimester | Safety data limited; no increased risk of major malformations in most studies, but risk cannot be excluded. |
| 2nd trimester | Use only if clearly needed; no known fetal risk based on limited data. |
| 3rd trimester | Use only if clearly needed; may cause maternal ECG changes (QT prolongation) at high doses. |
Clinical note
Comprehensive clinical and safety monograph for ZOFRAN PRESERVATIVE FREE (ZOFRAN PRESERVATIVE FREE).
| Placental transfer | Ondansetron crosses the placenta with fetal plasma concentrations approximately 50-60% of maternal levels. |
| Breastfeeding | Ondansetron is excreted into breast milk in low concentrations; likely compatible with breastfeeding, but monitor infant for potential adverse effects such as drowsiness or constipation. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to ondansetron or any component of the formulationConcurrent use of apomorphineCongenital long QT syndrome
| Precautions | QTc interval prolongation (dose-dependent); serotonin syndrome (especially with concomitant serotonergic drugs); masked ileus or gastric distension; hypersensitivity reactions including anaphylaxis; electrolyte abnormalities (hypokalemia, hypomagnesemia) increase arrhythmia risk. |
| Food/Dietary | No significant food interactions. Avoid grapefruit juice as it may increase ondansetron levels. No dietary restrictions. |
| Clinical Pearls |
Loading safety data…
| Lactation Rating |
| L2 (Possibly Compatible) |
| Teratogenic Risk | First trimester: Limited human data; no increased risk of major malformations observed in epidemiological studies. Second and third trimesters: No evidence of fetal harm; ondansetron crosses placenta but no teratogenic effects reported. However, retrospective studies suggest a possible small increased risk of cleft palate with first-trimester use, not confirmed by large cohort studies. |
| Fetal Monitoring | Maternal: Monitor for QT interval prolongation on ECG in patients with electrolyte abnormalities or concurrent use of QT-prolonging drugs. Fetal: Standard prenatal care; no specific fetal monitoring required. Neonatal: Observe for extrapyramidal symptoms or serotonin syndrome if used near term. |
| Fertility Effects | No known adverse effects on human fertility. Animal studies show no impairment of fertility at doses up to 15 mg/kg/day. |
| Ondansetron is a 5-HT3 receptor antagonist used for prevention of nausea and vomiting. PF formulation contains no preservatives; single-dose vial for IV/IM use. Risk of QT prolongation: avoid in patients with congenital long QT syndrome, hypokalemia, hypomagnesemia, or concomitant use of other QT-prolonging drugs. ECG monitoring recommended in patients with electrolyte abnormalities or CHF. Maximum single IV dose: 16 mg diluted in 50 mL NS infused over 15 min. For prevention of nausea/vomiting in highly emetogenic chemotherapy, use with dexamethasone. Not effective for motion sickness or vertigo. |
| Patient Advice | This medication is used to prevent nausea and vomiting, not to treat existing symptoms. · It may cause headache, constipation, or dizziness; report any palpitations or fainting. · Avoid consuming alcohol while taking this medication. · Inform your doctor if you have heart problems, electrolyte imbalances, or are taking other medications that affect heart rhythm. · If you miss a dose, take it as soon as possible unless it is almost time for the next dose. Do not double dose. |