Ondansetron 8mg Tablets

Ondansetron is a selective 5-hydroxytryptamine3 (5-HT3) receptor antagonist. Chemotherapeutic agents and radiation therapy cause release of serotonin (5-HT) from enterochromaffin cells of the small intestine, which then activate 5-HT3 receptors located on vagal afferents to initiate the vomiting reflex. Ondansetron blocks the initiation of this reflex by antagonizing 5-HT3 receptors on both peripheral (vagal afferents in the GI tract) and central (chemoreceptor trigger zone, CTZ) neurons.

Urgent Side Effects: Seek Medical Help Right Away

Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:

Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Trouble passing urine
Dizziness
Sudden chest pain or tightness
Abnormal heartbeat, including a fast or irregular heartbeat, or fainting (this medication can cause a prolonged QT interval, which may lead to a potentially life-threatening abnormal heartbeat called torsades de pointes)
Serotonin syndrome, a severe and potentially life-threatening condition, which may be more likely to occur if you are taking certain other medications. Symptoms include:
+ Agitation
+ Change in balance
+ Confusion
+ Hallucinations
+ Fever
+ Fast or abnormal heartbeat
+ Flushing
+ Muscle twitching or stiffness
+ Seizures
+ Shivering or shaking
+ Excessive sweating
+ Severe diarrhea
+ Upset stomach or vomiting
+ Severe headache
Stomach pain or swelling of the stomach area, especially if you have had surgery in the stomach area or have experienced upset stomach and vomiting after chemotherapy (this medication may mask the signs of a bowel block)

Other Possible Side Effects

Most people do not experience significant side effects, but some may occur. If you notice any of the following side effects or any other unusual symptoms, contact your doctor or seek medical attention if they bother you or do not go away:

Headache
Feeling tired or weak
Diarrhea or constipation
Feeling sleepy
Anxiety

This is not an exhaustive list of possible side effects. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.

Before Taking This Medication: Important Information to Share with Your Doctor

It is essential to inform your doctor about the following:

Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
If you have a prolonged QT interval visible on an electrocardiogram (ECG).
* If you are currently taking apomorphine.

This list is not exhaustive, and it is crucial to discuss all your medications, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins, with your doctor and pharmacist. They will help determine if it is safe to take this medication in combination with your other medications and health conditions.

Remember, do not start, stop, or adjust the dosage of any medication without first consulting your doctor to ensure your safety.

It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. If you are pregnant, planning to become pregnant, or are breast-feeding, be sure to discuss this with your doctor. You and your doctor will need to carefully weigh the benefits and risks of this medication to both you and your baby.

• Apomorphine (concurrent use with ondansetron is contraindicated due to profound hypotension and loss of consciousness)

• QT-prolonging drugs (e.g., amiodarone, sotalol, quinidine, procainamide, disopyramide, dofetilide, dronedarone, chlorpromazine, thioridazine, pimozide, ziprasidone, haloperidol, methadone, citalopram, escitalopram, moxifloxacin, erythromycin, pentamidine, tricyclic antidepressants) - increased risk of Torsades de Pointes
• Tramadol (increased risk of serotonin syndrome and reduced analgesic effect of tramadol)
• Serotonergic drugs (e.g., SSRIs, SNRIs, MAOIs, tricyclic antidepressants, lithium, triptans, fentanyl, linezolid, St. John's Wort) - increased risk of serotonin syndrome

• Phenytoin, Carbamazepine, Rifampin (strong CYP3A4 inducers may decrease ondansetron plasma concentrations)
• Dexamethasone (may increase ondansetron plasma concentrations and enhance antiemetic effect)
• Drugs that cause electrolyte abnormalities (e.g., diuretics) - increased risk of QT prolongation

• Nausea
• Vomiting
• Headache
• Constipation
• Diarrhea
• Fatigue
• Dizziness
• Lightheadedness
• Palpitations
• Syncope
• Agitation
• Confusion
• Hallucinations
• Rapid heart rate
• High blood pressure
• Fever
• Muscle rigidity
• Tremor
• Seizures

Use during pregnancy should be considered only if the potential benefit justifies the potential risk to the fetus. Human data suggest no increased risk of major birth defects overall, but some studies have suggested a small increased risk of oral clefts (e.g., cleft lip/palate) with first-trimester exposure. The FDA has removed pregnancy categories and now uses the Pregnancy and Lactation Labeling Rule (PLLR).

Limited human data indicate that ondansetron is excreted into human milk. The amount ingested by the infant is small. Monitor breastfed infants for potential adverse effects such as constipation or diarrhea. Use with caution.

Safety and effectiveness have not been established in pediatric patients younger than 6 months of age. Dosing varies by age and weight for CINV. Monitor for QT prolongation, especially in patients with risk factors.

No dosage adjustment is generally required based on age alone. However, greater sensitivity of some older individuals cannot be ruled out. Elderly patients may have a higher incidence of cardiac arrhythmias and QT prolongation, so caution is advised, especially with IV administration.

• Ondansetron is highly effective for chemotherapy-induced and postoperative nausea and vomiting, but less effective for motion sickness.
• Administer before the emetogenic event (chemotherapy, surgery) for optimal prophylactic effect.
• Be aware of the potential for QT prolongation, especially with higher doses, rapid IV infusion, or in patients with pre-existing cardiac conditions or electrolyte imbalances.
• Monitor for serotonin syndrome when co-administered with other serotonergic agents.
• Common side effects include headache, constipation, and diarrhea.
• Oral disintegrating tablets (ODT) are available for patients who have difficulty swallowing or are actively vomiting.

• Granisetron (another 5-HT3 antagonist)
• Palonosetron (another 5-HT3 antagonist, longer half-life)
• Dolasetron (another 5-HT3 antagonist)
• Dexamethasone (corticosteroid, often used in combination with 5-HT3 antagonists for CINV)
• Neurokinin-1 (NK1) receptor antagonists (e.g., aprepitant, fosaprepitant, rolapitant, netupitant/palonosetron combination) - for highly emetogenic chemotherapy
• Dopamine receptor antagonists (e.g., prochlorperazine, metoclopramide) - for less severe nausea/vomiting
• Antihistamines (e.g., promethazine, dimenhydrinate) - for motion sickness or mild nausea
• Cannabinoids (e.g., dronabinol, nabilone) - for refractory CINV

If your symptoms or health issues persist or worsen, it is essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so it's a good idea to check with your pharmacist for more information. If you have any questions or concerns about this medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When seeking help, be prepared to provide details about what was taken, the amount, and the time it occurred.