Ondansetron

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Generic Name of Ondansetron - Learn More

Ondansetron

Ondansetron Precaution - What You Need to Know

- Cardiac Precautions: Ondansetron can prolong the QT interval, which is a measure of the heart's electrical activity. This can lead to a serious heart rhythm problem called Torsade de Pointes. Therefore, it should be avoided in patients with congenital long QT syndrome, a condition that predisposes individuals to this type of arrhythmia.
- Myocardial Ischemia: There have been reports of myocardial ischemia (reduced blood flow to the heart) in patients treated with ondansetron, particularly during intravenous administration. Symptoms can appear immediately after administration but usually resolve with prompt treatment. Coronary artery spasm is often the underlying cause, so it's crucial to monitor patients for signs of myocardial ischemia during and after administration.
- Serotonin Syndrome: Ondansetron can interact with other serotonergic drugs, such as selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), and monoamine oxidase inhibitors (MAOIs). This interaction can lead to serotonin syndrome, a potentially life-threatening condition characterized by symptoms such as agitation, hallucinations, rapid heart rate, and high blood pressure. Some cases of serotonin syndrome associated with ondansetron have been fatal.
- Hypersensitivity Reactions: Ondansetron can cause hypersensitivity reactions, including anaphylaxis, a severe and potentially life-threatening allergic reaction. Symptoms may include difficulty breathing, swelling of the face or throat, and hives. Patients with a history of allergies should be monitored closely when starting ondansetron.
- Masking of Progressive Ileus and Gastric Distension: Ondansetron should not be used as a substitute for nasogastric suction in patients with progressive ileus (a condition where the intestines stop moving) or gastric distension (abnormal enlargement of the stomach). The drug can mask the symptoms of these conditions, leading to delayed diagnosis and treatment.
- Pregnancy and Breastfeeding: While ondansetron is sometimes used off-label to treat morning sickness, there is limited data on its safety during pregnancy. Some studies have suggested a potential risk of birth defects, such as heart abnormalities and cleft palates, when used during the first trimester. Therefore, it should be used with caution in pregnant women and only under the supervision of a healthcare provider.
- Drug Interactions: Ondansetron can interact with various medications, including apomorphine, a drug used to treat Parkinson's disease. Concomitant use of ondansetron and apomorphine can cause a significant drop in blood pressure, leading to loss of consciousness. It's essential to inform your healthcare provider about all medications you are taking before starting ondansetron.
- Pediatric Use: Ondansetron is generally safe for use in children, but appropriate studies have not been performed in children younger than 4 years of age. Therefore, its use in this age group should be carefully considered and monitored by a healthcare provider.
- Geriatric Use: There are no specific problems identified that would limit the usefulness of ondansetron in the elderly. However, older adults may be more sensitive to the drug's side effects, particularly those affecting the heart, so caution is advised.
- Storage and Handling: Ondansetron should be stored at room temperature between 68°F to 77°F (20°C to 25°C). It can be exposed to temperatures between 59°F to 86°F (15°C to 30°C) for short periods, such as during transportation. It should be kept in a cool, dry place, away from heat and moisture.

Ondansetron Indication - Uses and Benefits

- Chemotherapy-Induced Nausea and Vomiting (CINV): Ondansetron is primarily used to prevent nausea and vomiting associated with cancer chemotherapy. It is effective in managing both acute and delayed CINV, making it a standard part of antiemetic regimens for cancer patients.
- Radiation-Induced Nausea and Vomiting (RINV): Ondansetron is also indicated for the prevention of nausea and vomiting caused by radiation therapy, particularly in patients receiving total body irradiation or high-dose radiation to the abdomen.
- Postoperative Nausea and Vomiting (PONV): Ondansetron is commonly used to prevent and treat PONV. It is often administered before surgery to reduce the risk of nausea and vomiting after anesthesia, especially in patients undergoing procedures with a high risk of PONV.
- Off-Label Uses: Ondansetron is sometimes used off-label for conditions not approved by regulatory authorities. For example, it may be prescribed for the management of nausea and vomiting associated with pregnancy, although this use is not officially approved and should be carefully considered due to potential risks.
- Pediatric Use: Ondansetron is approved for use in children as young as one month old for the prevention of CINV and PONV. It is also used in pediatric populations to treat acute gastroenteritis and cyclic vomiting syndrome, although these uses are off-label.
- Mechanism of Action: Ondansetron works by blocking serotonin 5-HT3 receptors, which are involved in the transmission of signals that trigger nausea and vomiting. By inhibiting these receptors, ondansetron prevents the activation of the vomiting center in the brain, thereby reducing symptoms of nausea and vomiting.
- Dosage Forms: Ondansetron is available in various forms, including tablets, orally disintegrating tablets, oral solution, and injectable solution. The choice of formulation depends on the patient's needs and the clinical setting. For example, the injectable form is often used in hospital settings for rapid onset of action.
- Dosing Regimens: The dosing of ondansetron varies depending on the indication. For CINV, it is typically given 30 minutes before chemotherapy, with additional doses given as needed. For PONV, it is usually administered just before surgery. The oral solution and orally disintegrating tablets are convenient for patients who have difficulty swallowing pills.
- Efficacy and Safety: Ondansetron is included in the World Health Organization's List of Essential Medicines, which highlights its importance and effectiveness in managing nausea and vomiting. Its safety profile has been well-established through extensive clinical use, making it a reliable option for various patient populations.
- Contraindications: Ondansetron is contraindicated in patients with known hypersensitivity to the drug or any of its components. It should also be used with caution in patients with certain medical conditions, such as congenital long QT syndrome, due to the risk of QT interval prolongation and Torsade de Pointes.

Ondansetron Contraindications - Important Warnings

- Hypersensitivity Reactions: Ondansetron is contraindicated in patients with a known hypersensitivity to the drug or any of its components. Hypersensitivity reactions, including anaphylaxis, have been reported with ondansetron use. Symptoms may include difficulty breathing, swelling of the face or throat, and hives.
- Congenital Long QT Syndrome: Ondansetron should be avoided in patients with congenital long QT syndrome, a condition that predisposes individuals to a type of heart rhythm problem called Torsade de Pointes. Ondansetron can prolong the QT interval, increasing the risk of this potentially life-threatening arrhythmia.
- Concomitant Use with Apomorphine: The concomitant use of ondansetron and apomorphine, a drug used to treat Parkinson's disease, is contraindicated. This combination can cause a significant drop in blood pressure, leading to loss of consciousness.
- Serotonin Syndrome Risk: Ondansetron should not be used in combination with other serotonergic drugs, such as selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), and monoamine oxidase inhibitors (MAOIs), due to the risk of serotonin syndrome. This condition can be life-threatening and is characterized by symptoms such as agitation, hallucinations, rapid heart rate, and high blood pressure.
- Pregnancy Considerations: While ondansetron is sometimes used off-label to treat morning sickness, its use during pregnancy should be carefully considered. Some studies have suggested a potential risk of birth defects, such as heart abnormalities and cleft palates, when used during the first trimester. Therefore, it should be used only under the supervision of a healthcare provider.
- Pediatric Use: Ondansetron is generally safe for use in children, but appropriate studies have not been performed in children younger than 4 years of age. Its use in this age group should be carefully considered and monitored by a healthcare provider.
- Geriatric Use: There are no specific problems identified that would limit the usefulness of ondansetron in the elderly. However, older adults may be more sensitive to the drug's side effects, particularly those affecting the heart, so caution is advised.
- Myocardial Ischemia: Ondansetron has been associated with myocardial ischemia, particularly during intravenous administration. Coronary artery spasm is often the underlying cause, so patients with a history of heart disease should be monitored closely when using ondansetron.
- Masking of Progressive Ileus and Gastric Distension: Ondansetron should not be used as a substitute for nasogastric suction in patients with progressive ileus or gastric distension. The drug can mask the symptoms of these conditions, leading to delayed diagnosis and treatment.
- Storage and Handling: Ondansetron should be stored at room temperature between 68°F to 77°F (20°C to 25°C). It can be exposed to temperatures between 59°F to 86°F (15°C to 30°C) for short periods, such as during transportation. It should be kept in a cool, dry place, away from heat and moisture.

Ondansetron Side Effects - What to Expect

- Common Side Effects: The most common side effects of ondansetron include headache, fatigue, and constipation. These side effects are usually mild and resolve on their own without the need for medical intervention.
- Cardiovascular Side Effects: Ondansetron can cause QT interval prolongation, which is a measure of the heart's electrical activity. This can lead to a serious heart rhythm problem called Torsade de Pointes. Symptoms may include fainting, dizziness, and heart palpitations.
- Gastrointestinal Side Effects: In addition to constipation, ondansetron can cause other gastrointestinal side effects such as diarrhea, abdominal pain, and nausea. These side effects are usually mild and can be managed with supportive care.
- Neurological Side Effects: Ondansetron can cause neurological side effects such as headache, dizziness, and drowsiness. These side effects are usually mild but can be bothersome for some patients.
- Hypersensitivity Reactions: Ondansetron can cause hypersensitivity reactions, including anaphylaxis, a severe and potentially life-threatening allergic reaction. Symptoms may include difficulty breathing, swelling of the face or throat, and hives.
- Serotonin Syndrome: Ondansetron can interact with other serotonergic drugs, leading to serotonin syndrome. This condition is characterized by symptoms such as agitation, hallucinations, rapid heart rate, and high blood pressure. In severe cases, it can be life-threatening.
- Liver Enzyme Elevations: Ondansetron can cause elevations in liver enzymes, which are usually asymptomatic and resolve on their own. However, in rare cases, it can lead to more serious liver problems.
- Extrapyramidal Symptoms: Ondansetron has been associated with extrapyramidal symptoms, which are movement disorders that can include muscle spasms, restlessness, and tremors. These symptoms are usually mild and resolve on their own.
- Visual Disturbances: Ondansetron can cause visual disturbances, including blurred vision and temporary vision loss. These side effects are usually transient and resolve on their own.
- Respiratory Side Effects: Ondansetron can cause respiratory side effects such as shortness of breath and chest pain. These side effects are less common but can be serious and require medical attention.

Ondansetron Pregnancy Category ID - Safety Information

2

Ondansetron Mode of Action - How It Works

- Serotonin 5-HT3 Receptor Antagonism: Ondansetron works by blocking serotonin 5-HT3 receptors, which are involved in the transmission of signals that trigger nausea and vomiting. By inhibiting these receptors, ondansetron prevents the activation of the vomiting center in the brain, thereby reducing symptoms of nausea and vomiting.
- Central and Peripheral Effects: Ondansetron acts both centrally (in the brain) and peripherally (in the gut) to block 5-HT3 receptors. This dual action makes it effective in preventing nausea and vomiting caused by various stimuli, including chemotherapy, radiation, and surgery.
- Selective Antiemetic Action: Ondansetron is a selective antiemetic, meaning it specifically targets the receptors involved in nausea and vomiting without affecting other serotonin receptors. This selectivity contributes to its effectiveness and relatively low side effect profile.
- Rapid Onset of Action: Ondansetron has a rapid onset of action, making it suitable for use in acute settings such as postoperative nausea and vomiting (PONV) and chemotherapy-induced nausea and vomiting (CINV). Its effects can be seen within minutes of administration.
- Prolonged Duration of Action: Ondansetron has a prolonged duration of action, providing sustained relief from nausea and vomiting. This makes it effective for both acute and delayed symptoms, such as those experienced during chemotherapy.
- Minimal Sedative Effects: Unlike some other antiemetics, ondansetron has minimal sedative effects. This means it can be used without causing significant drowsiness, making it a preferred choice for patients who need to remain alert.
- Low Incidence of Extrapyramidal Symptoms: Ondansetron has a low incidence of extrapyramidal symptoms, which are movement disorders that can include muscle spasms, restlessness, and tremors. This makes it a safer option compared to some older antiemetics that are more likely to cause these side effects.
- Effective in Various Settings: Ondansetron is effective in preventing nausea and vomiting in various settings, including chemotherapy, radiation therapy, and surgery. Its versatility makes it a valuable tool in managing these symptoms across different patient populations.
- Well-Established Safety Profile: Ondansetron has a well-established safety profile, with extensive clinical use demonstrating its effectiveness and relatively low risk of serious side effects. This has contributed to its inclusion in the World Health Organization's List of Essential Medicines.
- Available in Multiple Formulations: Ondansetron is available in various formulations, including tablets, orally disintegrating tablets, oral solution, and injectable solution. This allows for flexible administration based on patient needs and clinical settings.

Ondansetron Drug Interactions - What to Avoid

- Serotonergic Drugs: Ondansetron can interact with other serotonergic drugs, such as selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), and monoamine oxidase inhibitors (MAOIs). This interaction can lead to serotonin syndrome, a potentially life-threatening condition characterized by symptoms such as agitation, hallucinations, rapid heart rate, and high blood pressure.
- Apomorphine: The concomitant use of ondansetron and apomorphine, a drug used to treat Parkinson's disease, is contraindicated. This combination can cause a significant drop in blood pressure, leading to loss of consciousness.
- QT-Prolonging Drugs: Ondansetron can prolong the QT interval, which is a measure of the heart's electrical activity. Therefore, it should be used with caution in patients taking other QT-prolonging drugs, as the combined effect can increase the risk of a serious heart rhythm problem called Torsade de Pointes.
- CYP3A4 Inhibitors: Ondansetron is metabolized by the liver enzyme CYP3A4. Drugs that inhibit this enzyme, such as ketoconazole, itraconazole, and clarithromycin, can increase the plasma concentration of ondansetron, potentially leading to increased side effects.
- CYP3A4 Inducers: Conversely, drugs that induce CYP3A4, such as rifampin, phenytoin, and carbamazepine, can decrease the plasma concentration of ondansetron, potentially reducing its effectiveness.
- Tramadol: The concomitant use of ondansetron and tramadol, a pain medication, can increase the risk of serotonin syndrome. This interaction is due to the serotonergic effects of both drugs.
- Methylene Blue: Intravenous methylene blue can interact with ondansetron, increasing the risk of serotonin syndrome. This combination should be avoided unless medically necessary, and patients should be closely monitored.
- Fentanyl: The concomitant use of ondansetron and fentanyl, a potent opioid analgesic, can also increase the risk of serotonin syndrome. This interaction is due to the serotonergic effects of both drugs.
- Lithium: The concomitant use of ondansetron and lithium, a drug used to treat bipolar disorder, can increase the risk of serotonin syndrome. This interaction is due to the serotonergic effects of both drugs.
- Alcohol: Alcohol can enhance the sedative effects of ondansetron, leading to increased drowsiness and dizziness. Patients should avoid alcohol while taking ondansetron to prevent these potential interactions.

Ondansetron Adult Dose - Recommended Dosage

- Oral Administration: For the prevention of nausea and vomiting associated with chemotherapy, the recommended adult dose of ondansetron is 8 mg taken 30 minutes before the start of chemotherapy. Additional doses of 8 mg can be taken every 8 hours for up to 5 days after chemotherapy.
- Intravenous Administration: For intravenous administration, the recommended dose is 0.15 mg/kg (up to a maximum of 16 mg) given 30 minutes before the start of chemotherapy. Additional doses of 0.15 mg/kg can be given 4 and 8 hours after the first dose.
- Postoperative Nausea and Vomiting (PONV): For the prevention of PONV, the recommended dose is 4 mg taken 1 hour before surgery. Alternatively, 4 mg can be given intravenously just before the induction of anesthesia.
- Radiation-Induced Nausea and Vomiting (RINV): For the prevention of RINV, the recommended dose is 8 mg taken 1 to 2 hours before radiation therapy. Additional doses of 8 mg can be taken every 8 hours for up to 5 days after radiation therapy.
- Maximum Daily Dose: The maximum daily dose of ondansetron should not exceed 32 mg. This is to minimize the risk of side effects, particularly QT interval prolongation, which can lead to serious heart rhythm problems.
- Dosing Adjustments: Dosing adjustments may be necessary for patients with liver disease, as ondansetron is metabolized by the liver. In patients with severe liver impairment, the total daily dose should not exceed 8 mg.
- Special Populations: In elderly patients or those with renal impairment, no specific dosing adjustments are required. However, these patients should be monitored closely for side effects, as they may be more sensitive to the drug's effects.
- Off-Label Uses: For off-label uses, such as the management of nausea and vomiting associated with pregnancy, the dosing regimen should be determined by a healthcare provider. Typically, a lower dose of 4 mg taken two to three times a day is used.
- Administration Tips: Ondansetron tablets should be swallowed whole with water. The orally disintegrating tablets should be placed on the tongue and allowed to dissolve completely before swallowing. The oral solution can be mixed with apple or apple-grape juice to improve the taste.
- Storage and Handling: Ondansetron should be stored at room temperature between 68°F to 77°F (20°C to 25°C). It can be exposed to temperatures between 59°F to 86°F (15°C to 30°C) for short periods, such as during transportation. It should be kept in a cool, dry place, away from heat and moisture.

Ondansetron Child Dose - Dosage for Children

- Age-Based Dosing: The dosing of ondansetron in children varies based on age and weight. For children aged 4 to 11 years, the recommended dose for the prevention of chemotherapy-induced nausea and vomiting is 4 mg taken 30 minutes before chemotherapy, with additional doses of 4 mg every 8 hours for up to 5 days.
- Weight-Based Dosing: For children aged 6 months to 4 years, the dose is based on weight. The recommended dose is 0.15 mg/kg (up to a maximum of 4 mg) given 30 minutes before chemotherapy, with additional doses of 0.15 mg/kg every 8 hours for up to 5 days.
- Intravenous Administration: For intravenous administration in children, the recommended dose is 0.15 mg/kg (up to a maximum of 16 mg) given 30 minutes before chemotherapy, with additional doses of 0.15 mg/kg 4 and 8 hours after the first dose.
- Postoperative Nausea and Vomiting (PONV): For the prevention of PONV in children, the recommended dose is 0.1 mg/kg (up to a maximum of 4 mg) given intravenously just before the induction of anesthesia.
- Maximum Daily Dose: The maximum daily dose of ondansetron in children should not exceed 0.5 mg/kg or 16 mg, whichever is less. This is to minimize the risk of side effects, particularly QT interval prolongation, which can lead to serious heart rhythm problems.
- Off-Label Uses: Ondansetron is sometimes used off-label in children for conditions such as acute gastroenteritis and cyclic vomiting syndrome. The dosing regimen for these uses should be determined by a healthcare provider.
- Special Populations: In children with liver disease, dosing adjustments may be necessary, as ondansetron is metabolized by the liver. In children with severe liver impairment, the total daily dose should not exceed 0.1 mg/kg or 4 mg, whichever is less.
- Administration Tips: Ondansetron tablets should be swallowed whole with water. The orally disintegrating tablets should be placed on the tongue and allowed to dissolve completely before swallowing. The oral solution can be mixed with apple or apple-grape juice to improve the taste.
- Storage and Handling: Ondansetron should be stored at room temperature between 68°F to 77°F (20°C to 25°C). It can be exposed to temperatures between 59°F to 86°F (15°C to 30°C) for short periods, such as during transportation. It should be kept in a cool, dry place, away from heat and moisture.
- Monitoring: Children taking ondansetron should be monitored for side effects, particularly QT interval prolongation. Regular ECG monitoring may be necessary in children with underlying heart conditions or those taking other QT-prolonging drugs.

Ondansetron Renal Dose - Dosage for Kidney Conditions

- General Considerations: Ondansetron is primarily metabolized by the liver and excreted in the urine and feces. Renal impairment does not significantly affect the pharmacokinetics of ondansetron, so dose adjustments are generally not required in patients with kidney disease.
- Mild to Moderate Renal Impairment: In patients with mild to moderate renal impairment (creatinine clearance 30-80 mL/min), no dose adjustment is necessary. The standard dosing regimen can be followed.
- Severe Renal Impairment: In patients with severe renal impairment (creatinine clearance less than 30 mL/min), including those on dialysis, no specific dose adjustment is recommended. However, these patients should be monitored closely for side effects, as they may be more sensitive to the drug's effects.
- Hemodialysis: Ondansetron is not significantly removed by hemodialysis. Therefore, no additional dose is needed after dialysis. The standard dosing regimen can be followed in patients undergoing hemodialysis.
- Elderly Patients: Elderly patients may have age-related renal impairment, but no specific dose adjustment is required based on age alone. However, elderly patients should be monitored closely for side effects, as they may be more sensitive to the drug's effects.
- Monitoring: Patients with renal impairment should be monitored for side effects, particularly QT interval prolongation, which can lead to serious heart rhythm problems. Regular ECG monitoring may be necessary in these patients.
- Dosing Regimen: The standard dosing regimen for ondansetron can be followed in patients with renal impairment. For the prevention of chemotherapy-induced nausea and vomiting, the recommended dose is 8 mg taken 30 minutes before chemotherapy, with additional doses of 8 mg every 8 hours for up to 5 days.
- Intravenous Administration: For intravenous administration in patients with renal impairment, the recommended dose is 0.15 mg/kg (up to a maximum of 16 mg) given 30 minutes before chemotherapy, with additional doses of 0.15 mg/kg 4 and 8 hours after the first dose.
- Postoperative Nausea and Vomiting (PONV): For the prevention of PONV in patients with renal impairment, the recommended dose is 4 mg taken 1 hour before surgery or given intravenously just before the induction of anesthesia.
- Storage and Handling: Ondansetron should be stored at room temperature between 68°F to 77°F (20°C to 25°C). It can be exposed to temperatures between 59°F to 86°F (15°C to 30°C) for short periods, such as during transportation. It should be kept in a cool, dry place, away from heat and moisture.