Antiemetic | Nausea and Vomiting Medication
Always consult with a healthcare professional before starting any medication. This information is for educational purposes only and should not replace professional medical advice.
Ondansetron is a class of antiemetics , which reduces nausea and vomiting. It is most effective drug in treatment of chemotherapy induced nausea and vomiting (CINV),post operative nausea and vomiting (PONV). Ondansetron is used in combination with other drugs like apripitants , glucocorticoid for maximum benefits.
Ondansetron act on 5HT3 receptor which are located in chemotactic trigger zone (CTZ) of brain. CTZ is located in medulla oblongata , a part of brain. Stimulation of this part of brain causes symptoms like nausea and vomiting. Ondansetron crosses blood brain barrier and blocks this receptors and stops feeling of nausea and vomiting. This class of drugs are also known as 5HT3 receptor antagonists
Ondansetron is commonly used to treat:
Adults : 4 to 8 mg every 8 to 12 hours is standard oral dose in adults
Children : 0.15 mg per kg administered every 8 hours ( oral or IV )
Before taking ondansetron, tell your doctor if you have:
Liver:caution is advised. Dose adjustment is needed in case of liver disease.
Kidney: standard dose of ondansetron is safe to use in kidney disease. If you have any pre-existing kidney disease,keep your doctor informed about this.Examples: Selective serotonin reuptake inhibitors (SSRIs, e.g., sertraline, fluoxetine), serotonin-norepinephrine reuptake inhibitors (SNRIs, e.g., venlafaxine), monoamine oxidase inhibitors (MAOIs), triptans (e.g., sumatriptan).
Mechanism: Ondansetron blocks 5-HT3 receptors, but when combined with drugs that increase serotonin levels, it may contribute to serotonin syndrome, a potentially lifethreatening condition characterized by symptoms such as confusion, agitation, sweating, tremors, and high fever
Examples: Antiarrhythmics (e.g., amiodarone, sotalol), antipsychotics (e.g., haloperidol,asenapine, ziprasidone), antibiotics (e.g., erythromycin, moxifloxacin), antifungals (e.g., fluconazole), and drugs like methadone, dronedarone
Mechanism: Ondansetron can prolong the QT interval, increasing the risk of torsades de pointes, a life-threatening arrhythmia. Combining it with other QT-prolonging drugs heightens this risk, especially in patients with heart failure, electrolyte abnormalities (e.g., hypokalemia, hypomagnesemia), or congenital long QT syndrome.
Inhibitors: Ketoconazole, ritonavir, atazanavir (CYP3A4); fluoxetine, quinidine (CYP2D6); fluvoxamine (CYP1A2).
Inducers: Phenytoin, carbamazepine, rifampin, apalutamide (CYP3A4).
Mechanism: Ondansetron is metabolized by hepatic cytochrome P-450 enzymes (CYP3A4, CYP2D6, CYP1A2). Inhibitors may increase ondansetron plasma levels, potentially leading to enhanced side effects (e.g., headache, constipation, or QT prolongation), while inducers may decrease its efficacy by increasing excretion
In case of overdose, contact poison control immediately at 1-800-222-1222 or seek emergency medical attention. Symptoms of overdose may include severe nausea, vomiting, stomach pain, confusion, ringing in ears, fever, and difficulty breathing.