ZOFRAN ODT
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ZOFRAN ODT (ZOFRAN ODT).
Selective antagonist of serotonin 5-HT3 receptors, blocking serotonin binding in the chemoreceptor trigger zone and gastrointestinal tract, thereby inhibiting emesis.
| Metabolism | Hepatic via CYP1A2, CYP2D6, and CYP3A4 |
| Excretion | Renal (47% as unchanged drug and metabolites, primarily glucuronide conjugates) and hepatic metabolism; about 25% excreted in feces; less than 10% excreted unchanged in urine. |
| Half-life | Terminal elimination half-life approximately 3–6 hours in adults; prolonged to 8–15 hours in patients with severe hepatic impairment (Child-Pugh C) due to reduced clearance. |
| Protein binding | 70–76% bound to plasma proteins (mainly albumin). |
| Volume of Distribution | Volume of distribution 1.7–2.5 L/kg; wide distribution suggests extensive tissue binding. |
| Bioavailability | Oral bioavailability approximately 60% due to first-pass metabolism; bioavailability of ODT formulation is similar to conventional oral tablet (~60% relative to IV). |
| Onset of Action | Orally disintegrating tablet: Onset of antiemetic effect within 30 minutes to 2 hours; peak plasma concentration at 1–2 hours. |
| Duration of Action | Duration of antiemetic effect approximately 12–24 hours; clinical trials show efficacy for prevention of chemotherapy-induced nausea and vomiting for up to 24 hours after dosing. |
| Molecular Weight | 293.36 |
8 mg orally disintegrating tablet (ODT) 30 minutes before chemotherapy; for prevention of nausea/vomiting, 8 mg orally twice daily.
| Dosage form | TABLET, ORALLY DISINTEGRATING |
| Renal impairment | No dosage adjustment required for mild to moderate renal impairment. For severe renal impairment (CrCl <30 mL/min), maximum daily dose of 8 mg. |
| Liver impairment | Severe hepatic impairment (Child-Pugh C): maximum total daily dose of 8 mg. |
| Pediatric use | For chemotherapy-induced nausea/vomiting: 0.15 mg/kg/dose IV (max 16 mg) 30 minutes before chemotherapy, then every 4 hours as needed. For radiation-induced: weight ≥30 kg: 8 mg ODT 1-2 hours before radiation; weight <30 kg: 4 mg ODT. For postoperative nausea/vomiting: 0.1 mg/kg IV (max 4 mg) at induction. |
| Geriatric use | No specific dose adjustment; use caution in elderly due to potential QT prolongation risk, and consider reduced starting doses if renal or hepatic function is compromised. |
| 1st trimester | Limited human data; animal studies show no teratogenicity. Use only if clearly needed. |
| 2nd trimester | No known fetal harm from limited data; does not appear to increase major malformations. |
| 3rd trimester | No known adverse fetal/neonatal effects; use if benefit outweighs risk. |
Clinical note
Comprehensive clinical and safety monograph for ZOFRAN ODT (ZOFRAN ODT).
| Placental transfer | Crosses placenta extensively; umbilical cord/maternal plasma concentration ratio ~0.95. |
| Breastfeeding | Ondansetron enters breast milk in low amounts (estimated 0.21-0.38% of maternal weight-adjusted dose). No adverse effects in infants reported; caution with preterm or low-weight infants. |
| Lactation Rating |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to ondansetron or any componentConcomitant use of apomorphine
| Precautions | Serotonin syndrome when used with other serotonergic drugs; QT prolongation (dose-dependent); masked progressive ileus/gastric distension; hypersensitivity reactions; use in patients with hepatic impairment may require dose adjustment |
| Food/Dietary | No significant food interactions. However, grapefruit juice may slightly increase ondansetron plasma levels (via CYP3A4 inhibition), but clinical relevance is minimal. No specific dietary restrictions. Can be taken with or without food. Caution with high-tyramine foods in patients on MAO inhibitors (rare combination). |
Loading safety data…
| L2 (Safer) |
| Teratogenic Risk | Ondansetron (Zofran ODT) is classified as FDA Pregnancy Category B. Large cohort studies do not show a statistically significant increased risk of major congenital malformations overall. Some studies suggest a possible small increased risk of cleft palate (odds ratio ~1.24) when used in the first trimester, but data are conflicting. No consistent evidence of other malformations. Second and third trimester use is not associated with structural defects. Risk of preterm birth or low birth weight not clearly increased. |
| Fetal Monitoring | Monitor maternal ECG if risk factors for QT prolongation (e.g., electrolyte abnormalities, concomitant QT-prolonging drugs). Assess for signs of serotonin syndrome, especially if used with other serotonergic agents. Fetal monitoring not routinely required unless maternal complications arise. In pregnancy, monitor for severe nausea and vomiting to prevent dehydration and electrolyte imbalances. |
| Fertility Effects | No specific adverse effects on fertility have been reported in humans. Animal studies did not show impairment of fertility at doses up to 15 mg/kg/day. However, severe nausea and vomiting may indirectly affect reproductive health; treating such conditions may facilitate conception. |
| Clinical Pearls |
| ZOFRAN ODT (ondansetron orally disintegrating tablet) is a 5-HT3 receptor antagonist used for prevention of nausea and vomiting due to chemotherapy, radiotherapy, and surgery. It dissolves on the tongue without water, making it ideal for patients with nausea. QT prolongation risk: avoid use in patients with congenital long QT syndrome, electrolyte abnormalities, or concurrent use of other QT-prolonging drugs. Correct hypokalemia and hypomagnesemia before administration. Do not exceed 16 mg single IV dose (oral doses up to 24 mg have been used but with increased QT risk). For chemotherapy-induced nausea, give 30 minutes before chemotherapy. Can cause serotonin syndrome when combined with other serotonergic drugs. Hepatic impairment: reduce dose in severe impairment (Child-Pugh class C: max 8 mg/day). |
| Patient Advice | Take this medication exactly as prescribed, usually 30 minutes before chemotherapy or surgery. · Do not remove the tablet from the blister pack until ready to take. Peel back the foil, do not push through. · Place the tablet on the tongue and allow it to dissolve completely (usually a few seconds), then swallow with saliva. No water needed. · May cause drowsiness, dizziness, or blurred vision. Avoid driving or operating machinery until you know how it affects you. · Contact your doctor immediately if you experience irregular heartbeat, fainting, severe constipation, or signs of serotonin syndrome (agitation, hallucinations, rapid heart rate, fever, muscle stiffness, loss of coordination). · Avoid alcohol and other CNS depressants as they may increase drowsiness. · If you have liver problems or a history of heart rhythm disorders (especially long QT syndrome), inform your doctor before use. |