Ondansetron 4mg/2ml Inj, 2ml

Ondansetron is a selective 5-hydroxytryptamine3 (5-HT3) receptor antagonist. Serotonin 5-HT3 receptors are located both peripherally on vagal nerve terminals in the gastrointestinal tract and centrally in the chemoreceptor trigger zone (CTZ) of the area postrema. Chemotherapeutic agents and radiation therapy cause release of serotonin from enterochromaffin cells in the small intestine, which then activates vagal afferents via 5-HT3 receptors, initiating the vomiting reflex. Ondansetron blocks this action, thereby preventing nausea and vomiting.

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 immediately or seek emergency 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 (fast or irregular) or fainting, as this medication can cause a type of abnormal heartbeat (prolonged QT interval), which may lead to another type of unsafe abnormal heartbeat (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, as 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 symptoms or any other unusual effects, contact your doctor for advice:

Headache
Feeling tired or weak
Diarrhea or constipation
Feeling sleepy
Anxiety

This is not an exhaustive list of possible side effects. If you have concerns or questions, 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 and its symptoms.
If you have a prolonged QT interval 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 existing treatments and health conditions.

Remember, do not start, stop, or modify the dosage 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 benefits and risks of taking this medication to both you and your baby, allowing you to make an informed decision.

• Apomorphine (risk of profound hypotension and loss of consciousness)

• Drugs that prolong the QT interval (e.g., amiodarone, sotalol, quinidine, procainamide, disopyramide, dofetilide, chlorpromazine, haloperidol, thioridazine, pimozide, moxifloxacin, erythromycin, pentamidine, methadone, citalopram, escitalopram, fluoxetine, sertraline, tricyclic antidepressants)
• Tramadol (may reduce analgesic effect of tramadol and increase risk of serotonin syndrome)

• Phenytoin (decreased ondansetron plasma concentrations)
• Carbamazepine (decreased ondansetron plasma concentrations)
• Rifampin (decreased ondansetron plasma concentrations)
• Serotonergic drugs (e.g., SSRIs, SNRIs, MAOIs, tricyclic antidepressants, lithium, fentanyl, tramadol, triptans, St. John's Wort - increased risk of serotonin syndrome)

• Not specifically identified as clinically significant minor interactions.

• Headache
• Constipation
• Diarrhea
• Dizziness
• Fatigue
• Rash
• Hypersensitivity reactions (e.g., anaphylaxis, angioedema)
• Symptoms of QT prolongation (e.g., palpitations, lightheadedness, syncope)
• Symptoms of serotonin syndrome (e.g., agitation, hallucinations, rapid heart rate, fever, sweating, shivering, muscle twitching, rigidity, incoordination, nausea, vomiting, diarrhea)

Ondansetron is generally considered for use in pregnancy only if clearly needed, particularly for severe nausea and vomiting of pregnancy (NVP) refractory to other treatments. While older classifications listed it as Category B, current data are mixed regarding a potential small increased risk of oral clefts or cardiac defects when used in the first trimester. Clinical guidelines often recommend it as a second-line or third-line agent.

Ondansetron is excreted into human milk. While the amount is generally low, caution is advised. Monitor breastfed infants for potential side effects such as constipation or diarrhea. Use only if the potential benefit justifies the potential risk to the infant.

Dosing is weight-based and age-dependent. Safety and efficacy established for CINV in children 6 months and older, and for PONV in children 1 month and older. Monitor for QT prolongation, especially in younger children or those with underlying cardiac conditions.

No specific dose adjustment is required based solely on age. However, elderly patients may have reduced hepatic or renal function, which could affect drug clearance. They may also be more susceptible to QT prolongation due to polypharmacy or underlying cardiac conditions. Monitor ECG and electrolytes closely.

• Administer IV ondansetron slowly over 2-5 minutes (or 15 minutes for higher doses) to minimize the risk of transient vision changes or dizziness.
• Be aware of the risk of serotonin syndrome when co-administered with other serotonergic drugs. Educate patients on symptoms.
• Correct hypokalemia and hypomagnesemia prior to ondansetron administration to reduce the risk of QT prolongation.
• Ondansetron is not effective for motion sickness.
• While generally well-tolerated, constipation is a common side effect, especially with repeated dosing.

• Other 5-HT3 receptor antagonists (e.g., granisetron, palonosetron, dolasetron)
• Neurokinin-1 (NK1) receptor antagonists (e.g., aprepitant, fosaprepitant, netupitant/palonosetron combination)
• Corticosteroids (e.g., dexamethasone)
• Dopamine receptor antagonists (e.g., prochlorperazine, metoclopramide, droperidol)
• Antihistamines (e.g., promethazine, dimenhydrinate)
• Cannabinoids (e.g., dronabinol, nabilone)

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. Dispose of unused or expired medications properly. Unless instructed to do so by a healthcare professional, avoid flushing medications down the toilet or pouring them down the drain. If you are unsure about the proper disposal method, consult your pharmacist, who can also inform you about potential drug take-back programs in your area. Some medications may come with an additional patient information leaflet, which your pharmacist can provide. If you have any questions or concerns 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.