Ondansetron 4mg/5ml Solution
It is used to treat or prevent upset stomach and throwing up.
Drug Class
Antiemetic
Pharmacologic Class
Selective 5-HT3 Receptor Antagonist
Pregnancy Category
Not available
FDA Approved
Jan 1991
DEA Schedule
Not Controlled
Overview
What is this medicine?
Ondansetron is a medicine used to prevent and treat nausea and vomiting. It works by blocking a natural substance in your body (serotonin) that can cause you to feel sick to your stomach. It's commonly used for nausea caused by chemotherapy, radiation, or surgery.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. You can take this medication with or without food. If you're using the liquid form, measure your dose carefully using the measuring device that comes with the medication. If one isn't provided, ask your pharmacist for a suitable measuring device.
Storing and Disposing of Your Medication
Store your medication at room temperature, protected from light, and in a dry place. Avoid storing it in a bathroom. Keep the medication upright with the cap on. Ensure that all medications are kept in a safe location, out of the reach of children and pets. When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so. Instead, consult your pharmacist for guidance on the best disposal method or inquire about potential drug take-back programs in your area.
Missing a Dose
If you take this medication regularly and miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses. If you take this medication as needed, follow your doctor's instructions and do not take it more frequently than recommended.
To use this medication correctly, follow your doctor's instructions and read all the information provided. You can take this medication with or without food. If you're using the liquid form, measure your dose carefully using the measuring device that comes with the medication. If one isn't provided, ask your pharmacist for a suitable measuring device.
Storing and Disposing of Your Medication
Store your medication at room temperature, protected from light, and in a dry place. Avoid storing it in a bathroom. Keep the medication upright with the cap on. Ensure that all medications are kept in a safe location, out of the reach of children and pets. When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so. Instead, consult your pharmacist for guidance on the best disposal method or inquire about potential drug take-back programs in your area.
Missing a Dose
If you take this medication regularly and miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses. If you take this medication as needed, follow your doctor's instructions and do not take it more frequently than recommended.
Lifestyle & Tips
- Take this medication exactly as prescribed by your doctor. Do not take more or less than directed.
- Measure the oral solution carefully using the provided measuring device (oral syringe or cup) to ensure you get the correct dose.
- You can take this medication with or without food.
- If you miss a dose, take it as soon as you remember. If it's close to your next dose, skip the missed dose and continue your regular schedule. Do not double doses.
- Stay hydrated, especially if you are experiencing vomiting or diarrhea.
- Report any unusual side effects, especially severe dizziness, fainting, chest pain, or irregular heartbeat, to your doctor immediately.
Available Forms & Alternatives
Available Strengths:
- Ondansetron ODT 8mg Tablets
- Ondansetron ODT 4mg Tablets
- Ondansetron 4mg/5ml Solution
- Ondansetron 2mg/ml Inj, 2ml
- Ondansetron 8mg Tablets
- Ondansetron 4mg Tablets
- Ondansetron 8mg Tablets
- Ondansetron 4mg Tablets
- Ondansetron 4mg/2ml Inj, 2ml
- Ondansetron 4mg Tablets
- Ondansetron 40mg/20ml Inj, 20ml
- Ondansetron 4mg/2ml Pf Syr Inj, 2ml
Dosing & Administration
Adult Dosing
Standard Dose:
Varies by indication. For CINV (moderately emetogenic): 8 mg (10 ml) orally twice daily, first dose 30 minutes before chemotherapy. For PONV: 16 mg (20 ml) orally as a single dose 1 hour before induction of anesthesia.
Dose Range:
4 - 24 mg
Condition-Specific Dosing:
Chemotherapy-Induced Nausea and Vomiting (CINV) - Highly Emetogenic:
24 mg (30 ml) orally as a single dose 30 minutes before chemotherapy.
Chemotherapy-Induced Nausea and Vomiting (CINV) - Moderately Emetogenic:
8 mg (10 ml) orally twice daily, first dose 30 minutes before chemotherapy, then every 8 hours for 1-2 days after chemotherapy.
Postoperative Nausea and Vomiting (PONV):
16 mg (20 ml) orally as a single dose 1 hour before induction of anesthesia.
Radiation-Induced Nausea and Vomiting (RINV) - Total Body Irradiation:
8 mg (10 ml) orally 1-2 hours before each fraction of radiotherapy.
Radiation-Induced Nausea and Vomiting (RINV) - Single High-Dose Fraction:
8 mg (10 ml) orally 1-2 hours before radiation, then every 8 hours for 1-2 days after radiation.
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established for oral solution under 6 months. For CINV (6 months to <12 years, BSA <0.3 m²): 2 mg (2.5 ml) orally 30 minutes before chemotherapy, then 4 and 8 hours after the first dose, then every 8 hours for 1-2 days. (Dosing varies by BSA/weight and emetogenicity).
Child:
For CINV (6 months to <12 years, BSA ≥0.3 m²): 4 mg (5 ml) orally 30 minutes before chemotherapy, then 4 and 8 hours after the first dose, then every 8 hours for 1-2 days. For PONV (≥12 years): 16 mg (20 ml) orally as a single dose 1 hour before induction of anesthesia.
Adolescent:
For CINV (≥12 years): Same as adult dosing. For PONV: 16 mg (20 ml) orally as a single dose 1 hour before induction of anesthesia.
Dose Adjustments
Renal Impairment:
Mild:
No adjustment needed
Moderate:
No adjustment needed
Severe:
No adjustment needed
Dialysis:
No adjustment needed; ondansetron is not significantly removed by dialysis.
Hepatic Impairment:
Mild:
No adjustment needed
Moderate:
No adjustment needed
Severe:
Maximum daily dose of 8 mg (10 ml) orally. Administer with caution.
Pharmacology
Mechanism of Action
Ondansetron is a selective 5-hydroxytryptamine3 (5-HT3) receptor antagonist. Serotonin 5-HT3 receptors are located on the vagal afferent neurons in the gastrointestinal tract and in the chemoreceptor trigger zone (CTZ) in the area postrema of the brain. Chemotherapeutic agents and radiation therapy cause the release of serotonin from enterochromaffin cells in the small intestine, which then activates 5-HT3 receptors on vagal afferents, initiating the vomiting reflex. Ondansetron blocks this action, thereby preventing nausea and vomiting.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 60% (due to first-pass metabolism)
Tmax:
1.5 to 2 hours
FoodEffect:
Food slightly increases the extent of absorption but does not significantly affect Tmax or clinical efficacy.
Distribution:
Vd:
Approximately 140 L
ProteinBinding:
70% to 76%
CnssPenetration:
Limited
Elimination:
HalfLife:
Approximately 3 to 6 hours (adults); shorter in children (2.9 hours in 1-4 years, 3.5 hours in 5-12 years)
Clearance:
Approximately 0.35 L/min/kg (adults)
ExcretionRoute:
Renal (approximately 5% as unchanged drug, 50-60% as metabolites), Fecal (25-30% as metabolites)
Unchanged:
Approximately 5%
Pharmacodynamics
OnsetOfAction:
Within 30 minutes (oral)
PeakEffect:
1.5 to 2 hours
DurationOfAction:
4 to 8 hours
Safety & Warnings
Side Effects
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 severe side effects, and many have 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, 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.
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 severe side effects, and many have 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, 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.
Seek Immediate Medical Attention If You Experience:
- Severe dizziness or fainting
- Chest pain or discomfort
- Fast, slow, or irregular heartbeat (palpitations)
- Severe headache
- Blurred vision or temporary vision loss
- Signs of an allergic reaction (e.g., rash, itching, swelling of the face/lips/tongue/throat, severe dizziness, trouble breathing)
- Signs of serotonin syndrome (e.g., agitation, confusion, hallucinations, rapid heart rate, sweating, muscle stiffness or twitching, fever, severe diarrhea)
Before Using This Medicine
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 disclose all your medications, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins, as well as any existing health problems, to your doctor and pharmacist. This will help ensure that it is safe for you to take this medication in conjunction with your other treatments and health conditions.
Remember, do not initiate, discontinue, or modify the dosage of any medication without first consulting your doctor to confirm that it is safe to do so.
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 disclose all your medications, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins, as well as any existing health problems, to your doctor and pharmacist. This will help ensure that it is safe for you to take this medication in conjunction with your other treatments and health conditions.
Remember, do not initiate, discontinue, or modify the dosage of any medication without first consulting your doctor to confirm that it is safe to do so.
Precautions & Cautions
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, you must discuss this with your doctor. This conversation will help you understand the benefits and risks of taking this drug, both for you and your baby, allowing you to make an informed decision.
Overdose Information
Overdose Symptoms:
- Severe constipation
- Hypotension (low blood pressure)
- Vasovagal episode with transient AV block
- Transient blindness
- Serotonin syndrome
- QT interval prolongation
- Torsades de Pointes
What to Do:
In case of overdose, seek immediate medical attention. Call your local poison control center (e.g., 1-800-222-1222 in the US) or emergency services. Treatment is supportive and symptomatic. ECG monitoring is recommended due to the risk of QT prolongation.
Drug Interactions
Contraindicated Interactions
- Apomorphine (concurrent use with ondansetron can cause profound hypotension and loss of consciousness)
Major Interactions
- Drugs that prolong the QT interval (e.g., amiodarone, sotalol, quinidine, procainamide, disopyramide, dofetilide, dronedarone, chlorpromazine, thioridazine, pimozide, ziprasidone, haloperidol, methadone, moxifloxacin, erythromycin, pentamidine, cisapride, dolasetron, granisetron, palonosetron) - increased risk of Torsades de Pointes.
- Serotonergic drugs (e.g., SSRIs, SNRIs, MAOIs, tricyclic antidepressants, mirtazapine, fentanyl, tramadol, linezolid, triptans) - increased risk of serotonin syndrome.
Moderate Interactions
- CYP3A4 inducers (e.g., phenytoin, carbamazepine, rifampin) - may decrease ondansetron plasma concentrations, potentially reducing efficacy.
- CYP2D6 inhibitors (e.g., fluoxetine, paroxetine) - may increase ondansetron plasma concentrations, but generally not clinically significant.
Minor Interactions
- Not specifically identified as minor, but general caution with drugs affecting GI motility.
Monitoring
Baseline Monitoring
ECG (Electrocardiogram)
Rationale: To assess baseline QT interval, especially in patients with pre-existing cardiac conditions, electrolyte abnormalities, or those taking other QT-prolonging medications.
Timing: Before initiation of therapy in at-risk patients.
Serum Electrolytes (Potassium, Magnesium)
Rationale: To identify and correct any electrolyte imbalances (hypokalemia, hypomagnesemia) that can increase the risk of QT prolongation.
Timing: Before initiation of therapy in at-risk patients.
Liver Function Tests (LFTs)
Rationale: To assess hepatic function, particularly in patients with known or suspected hepatic impairment, as dose adjustment is required in severe hepatic impairment.
Timing: Before initiation of therapy in patients with suspected hepatic impairment.
Routine Monitoring
Bowel Function
Frequency: Daily, especially during initial therapy
Target: Regular bowel movements
Action Threshold: Persistent constipation or diarrhea; consider laxatives for constipation or antidiarrheals for diarrhea.
Signs/Symptoms of Serotonin Syndrome
Frequency: Regularly, especially if co-administered with other serotonergic drugs
Target: Absence of symptoms
Action Threshold: Mental status changes (agitation, hallucinations, coma), autonomic instability (tachycardia, labile blood pressure, hyperthermia), neuromuscular aberrations (hyperreflexia, incoordination), and/or gastrointestinal symptoms (nausea, vomiting, diarrhea). Discontinue ondansetron and other serotonergic agents immediately.
ECG (QTc interval)
Frequency: As clinically indicated, especially in patients with risk factors for QT prolongation or on high doses.
Target: <450 ms (men), <470 ms (women)
Action Threshold: Significant QTc prolongation (>500 ms or increase of >60 ms from baseline). Consider dose reduction or discontinuation.
Symptom Monitoring
- Nausea and vomiting (efficacy)
- Headache
- Constipation
- Diarrhea
- Dizziness
- Fatigue
- Rash
- Signs of hypersensitivity reaction (e.g., swelling of face, lips, tongue, throat, difficulty breathing)
- Chest pain, palpitations, irregular heartbeat (potential QT prolongation)
- Changes in mental status, agitation, muscle rigidity, tremors, sweating (signs of serotonin syndrome)
Special Patient Groups
Pregnancy
Ondansetron is generally considered to have a low risk for use during pregnancy, particularly for severe nausea and vomiting of pregnancy (NVP) or hyperemesis gravidarum, when other measures have failed. However, use should be based on a careful risk-benefit assessment. Some studies have suggested a small, increased risk of oral clefts, but overall data are conflicting and do not establish a definitive causal link.
Trimester-Specific Risks:
First Trimester:
Potential for a small, increased risk of oral clefts (e.g., cleft lip/palate) based on some observational studies, though other studies have not confirmed this. Use with caution and only if clearly needed.
Second Trimester:
Generally considered safer than in the first trimester, as organogenesis is largely complete. Use if clinically indicated.
Third Trimester:
Generally considered safe for use in the third trimester for nausea and vomiting. No known adverse effects on fetal development or labor.
Lactation
Ondansetron is excreted into human breast milk. The amount transferred to the infant is relatively low. The American Academy of Pediatrics considers it compatible with breastfeeding. Monitor breastfed infants for potential adverse effects such as constipation or diarrhea.
Infant Risk:
Low risk. Monitor for gastrointestinal upset (constipation, diarrhea) or sedation in the infant.
Pediatric Use
Dosing is weight- or body surface area (BSA)-based for children, especially for chemotherapy-induced nausea and vomiting. The half-life is shorter in children compared to adults. Safety and efficacy in infants younger than 6 months have not been established for oral solution. Close monitoring for side effects is important.
Geriatric Use
No specific dose adjustment is required based on age alone. However, elderly patients may be at increased risk for QT prolongation due to age-related physiological changes, co-morbidities, and concomitant medications. Monitor ECG and electrolytes more closely in this population.
Clinical Information
Clinical Pearls
- Ondansetron is highly effective for preventing and treating chemotherapy-induced, radiation-induced, and postoperative nausea and vomiting.
- The oral solution provides flexibility for patients who have difficulty swallowing tablets or require precise dose adjustments.
- Be mindful of the potential for QT prolongation, especially in patients with underlying cardiac conditions, electrolyte imbalances, or those on other QT-prolonging drugs.
- Constipation is a common side effect; advise patients on preventive measures like increased fluid intake and fiber.
- While generally well-tolerated, be vigilant for signs of serotonin syndrome, particularly if co-administered with other serotonergic agents.
- For CINV, administer the first dose before chemotherapy to maximize efficacy.
Alternative Therapies
- NK1 receptor antagonists (e.g., aprepitant, fosaprepitant, netupitant/palonosetron combination) - often used in combination with 5-HT3 antagonists and corticosteroids for highly emetogenic chemotherapy.
- Corticosteroids (e.g., dexamethasone) - commonly used as adjuncts for antiemetic prophylaxis.
- Dopamine receptor antagonists (e.g., prochlorperazine, metoclopramide) - older class of antiemetics, may have more extrapyramidal side effects.
- Antihistamines (e.g., promethazine, diphenhydramine) - for mild nausea, often sedating.
- Cannabinoids (e.g., dronabinol, nabilone) - for refractory CINV.
Cost & Coverage
Average Cost:
Typically low (generic) per 50 ml bottle (4mg/5ml)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (most insurance plans)
General Drug Facts
If your symptoms or health issues persist or worsen, it's 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 be sure to check with your pharmacist for more information. If you have any questions or concerns about your 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 the medication taken, the amount, and the time it occurred.