Ondansetron 40mg/20ml Inj, 20ml

Ondansetron is a selective 5-HT3 receptor antagonist. Chemotherapeutic agents and radiation therapy cause release of serotonin (5-HT) from enterochromaffin cells of the small intestine, which then stimulates 5-HT3 receptors located on vagal afferent nerves to initiate the vomiting reflex. Ondansetron blocks the initiation of this reflex.

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 signs or symptoms, contact your doctor or seek medical attention immediately:

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 if you pass out (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
+ Sweating a lot
+ Severe diarrhea
+ Upset stomach or vomiting
+ Very bad 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

Like all medications, this drug can cause side effects. Many people experience no side effects or only minor ones. However, if you notice any of the following side effects or any other unusual symptoms, contact your doctor or seek medical attention:

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, contact 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 the symptoms that occurred.
If you have a condition known as long QT 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 with your other medications and health conditions.

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

It is essential to inform all of 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, you must discuss this with your doctor. This conversation will help you understand the potential benefits and risks of this medication to both you and your baby, allowing you to make an informed decision.

• Apomorphine (concurrent use may cause profound hypotension and loss of consciousness)
• Drugs that prolong QT interval (e.g., amiodarone, sotalol, quinidine, procainamide, disopyramide, dofetilide, dronedarone, chlorpromazine, thioridazine, mesoridazine, pimozide, ziprasidone, haloperidol, droperidol, methadone, citalopram, escitalopram, fluoxetine, sertraline, tricyclic antidepressants, macrolide antibiotics, fluoroquinolone antibiotics, azole antifungals) - increased risk of Torsades de Pointes
• Serotonergic drugs (e.g., SSRIs, SNRIs, MAOIs, tricyclic antidepressants, fentanyl, tramadol, mirtazapine, triptans, lithium, St. John's Wort) - increased risk of serotonin syndrome

• Phenytoin, Carbamazepine, Rifampin (CYP3A4 inducers - may decrease ondansetron plasma concentrations)
• Tramadol (ondansetron may reduce tramadol's analgesic effect by inhibiting CYP2D6-mediated formation of active metabolite)
• Dexamethasone (concurrent use with ondansetron for CINV is common and beneficial, but dexamethasone can induce CYP3A4, potentially affecting ondansetron levels slightly)

• Not available

• Nausea
• Vomiting
• Headache
• Constipation
• Diarrhea
• Fatigue
• Dizziness
• Lightheadedness
• Chest pain
• Palpitations
• Fainting (syncope)
• Muscle rigidity
• Agitation
• Confusion
• Diaphoresis (sweating)
• Tremor
• Myoclonus (jerking movements)

Ondansetron is classified as Pregnancy Category B. While animal studies have not shown harm, human studies are limited. It is generally considered safe for use during pregnancy when clinically indicated, particularly for severe nausea and vomiting of pregnancy (hyperemesis gravidarum), after careful consideration of risks and benefits.

Ondansetron is excreted into breast milk in small amounts. The American Academy of Pediatrics considers it compatible with breastfeeding. Lactation Risk Category L3 (Moderately Safe). Monitor breastfed infant for potential side effects such as constipation or diarrhea.

Safety and efficacy established for CINV in children 1 month to 18 years, and for PONV in children 1 month to 12 years. Dosing is weight-based for younger children. Use with caution in infants < 1 month due to limited data. Monitor for QT prolongation, especially in children with underlying cardiac conditions or electrolyte imbalances.

No dosage adjustment is generally required based on age alone. However, elderly patients may have reduced hepatic or renal function, which could affect drug clearance. They may also be more susceptible to QT prolongation and should be monitored for cardiac adverse events. The maximum single daily dose of 8 mg IV for patients with moderate to severe hepatic impairment also applies to elderly patients with such impairment.

• Administer IV ondansetron slowly over 15 minutes to minimize the risk of QT prolongation and other adverse effects.
• The 40mg/20ml vial is a concentrated solution (2mg/ml) and is typically a multi-dose vial or intended for specific high-dose regimens. Always verify the dose and concentration before administration.
• Correct electrolyte abnormalities (hypokalemia, hypomagnesemia) before administering ondansetron to reduce the risk of QT prolongation.
• Be aware of the risk of serotonin syndrome when co-administered with other serotonergic agents. Educate patients on symptoms.
• Ondansetron is highly effective for acute nausea and vomiting but less effective for delayed CINV; consider adding a corticosteroid (e.g., dexamethasone) for highly emetogenic chemotherapy.
• While generally well-tolerated, constipation is a common side effect; consider prophylactic laxatives if appropriate.

• Neurokinin-1 (NK1) receptor antagonists (e.g., Aprepitant, Fosaprepitant, Rolapitant, Netupitant/Palonosetron combination) - often used in combination with 5-HT3 antagonists and corticosteroids for CINV.
• Corticosteroids (e.g., Dexamethasone) - often used in combination with 5-HT3 antagonists for CINV and PONV.
• Dopamine receptor antagonists (e.g., Prochlorperazine, Metoclopramide, Haloperidol) - for various types of nausea/vomiting.
• Antihistamines/Anticholinergics (e.g., Promethazine, Scopolamine) - for motion sickness or PONV.
• Cannabinoids (e.g., Dronabinol, Nabilone) - for refractory CINV.

If your symptoms or health problems persist or worsen, it is essential to contact your doctor promptly. To ensure safe use, never share your medication with others, and do not take medication prescribed for someone else. Store all medications in a secure location, out of reach of children and pets, to prevent accidental ingestion. Properly dispose of unused or expired medications by checking with your pharmacist for guidance, as some communities have drug take-back programs. Unless instructed to do so, avoid flushing medications down the toilet or pouring them down the drain. If you have questions about disposing of your medication, consult your pharmacist. Additionally, some medications may come with a separate patient information leaflet, which your pharmacist can provide. If you have any concerns or questions about your medication, discuss them with your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately contact your local poison control center or seek medical attention. Be prepared to provide information about the medication taken, the amount, and the time it occurred.