ONDANSETRON HYDROCHLORIDE AND DEXTROSE IN PLASTIC CONTAINER
Clinical safety rating: safe
Drugs that prolong the QT interval may have additive effects Can cause QT prolongation and subsequent arrhythmias.
Selective serotonin 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; approximately 5% is metabolized via N-demethylation. |
| Excretion | Approximately 5% of ondansetron is excreted unchanged in urine; the remainder undergoes extensive hepatic metabolism via CYP1A2, CYP2D6, and CYP3A4, with metabolites excreted in urine (about 44-60% of total dose) and feces (about 33-38%). |
| Half-life | Terminal elimination half-life is approximately 3-6 hours in adults, but may be prolonged in elderly patients (up to 8 hours) and in patients with severe hepatic impairment (Child-Pugh class C: 15-32 hours). |
| Protein binding | 70-76% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Apparent volume of distribution (Vd) is approximately 1.9-2.2 L/kg, indicating extensive extravascular distribution. |
| Bioavailability | Oral bioavailability is approximately 60% due to first-pass metabolism; oral disintegrating tablet has similar bioavailability; intramuscular administration is not approved, but intravenous provides 100% bioavailability. |
| Onset of Action | Intravenous: onset within 1-2 minutes; Oral: onset within 30-60 minutes; Orally disintegrating tablet: similar to oral. |
| Duration of Action | Duration of antiemetic effect is approximately 4-8 hours following intravenous administration; oral dosing provides coverage for up to 12 hours, but dosing intervals are typically every 8-12 hours. |
8 mg IV or 0.15 mg/kg IV every 8 hours for 3 doses or 32 mg IV once over 15 minutes for prevention of chemotherapy-induced nausea, or 4 mg IV once over 2-5 minutes for prevention of postoperative nausea. IV infusion in D5W at concentrations up to 1 mg/mL.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment (CrCl >30 mL/min). For severe renal impairment (CrCl <30 mL/min), dosing interval may be increased to every 24 hours due to decreased clearance. |
| Liver impairment | For Child-Pugh Class C (severe hepatic impairment): maximum total daily dose of 8 mg IV due to reduced clearance and increased half-life. For Child-Pugh A or B: no adjustment necessary. |
| Pediatric use | For chemotherapy-induced nausea (age 6 months to 18 years): 0.15 mg/kg/dose IV (maximum 8 mg per dose) every 8 hours for 3 doses. For postoperative nausea (age 1 month to 12 years): 0.1 mg/kg IV (maximum 4 mg) as a single dose. Dosing based on actual body weight. |
| Geriatric use | No specific dose adjustment required for elderly patients based on age alone. Monitor for QT prolongation, electrolyte disturbances, and potential increased sensitivity to adverse effects (headache, constipation). Use with caution in patients >75 years due to decreased clearance and potential for increased drug exposure. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Drugs that prolong the QT interval may have additive effects Can cause QT prolongation and subsequent arrhythmias.
| FDA category | Human |
| Breastfeeding | Ondansetron is excreted into breast milk in low amounts (M/P ratio approximately 1.4). The relative infant dose is estimated 0.5-1.2% of maternal weight-adjusted dose. Considered compatible with breastfeeding; however, caution is advised due to potential for adverse effects (diarrhea, constipation) in nursing infants. |
| Teratogenic Risk |
■ FDA Black Box Warning
No FDA black box warning.
| Common Effects | Headache |
| Serious Effects |
["Hypersensitivity to ondansetron or any component of the formulation","Concomitant use of apomorphine (increased risk of profound hypotension and loss of consciousness)"]
| Precautions | ["QT interval prolongation and torsade de pointes, especially with electrolyte abnormalities or concomitant QTc-prolonging drugs","Serotonin syndrome risk when used with other serotonergic drugs","Masking of progressive ileus or gastric distension after abdominal surgery","Hypersensitivity reactions including anaphylaxis"] |
Loading safety data…
| First trimester: Limited human data; animal studies show no evidence of teratogenicity at clinically relevant doses. Second trimester: No specific risks identified. Third trimester: No known fetal risks. Overall: FDA Pregnancy Category B; not associated with major malformations. |
| Fetal Monitoring | No specific monitoring required beyond usual clinical observation. Monitor for maternal ECG changes (QT interval prolongation) in patients with electrolyte abnormalities, cardiac disease, or concurrent QT-prolonging drugs. Fetal monitoring not indicated. |
| Fertility Effects | No known adverse effects on fertility in human or animal studies. |