What is Ondansetron?
Ondansetron is a drug used for the treatment of nausea and vomiting induced by chemotherapy or post-operative. The product ingredients are: Ondansetron hydrochloride (hcl), Ondansetron hydrochloride dihydrate .
The brand names of Ondanstron in the United States are: Zofran, Zofran ODT, Zuplenz.
Ondansetron Mechanism of Action (MOA)
Powerful and highly selective antagonist of 5-HT3 receptors located in peripheral neurons and within the CNS.
Therapeutic indications, uses and benefits of Ondansetron
- In adults: control of nausea and vomiting induced by chemotherapy and cytotoxic radiotherapy, and prevention and treatment of postoperative nausea and vomiting.
- Children ≥ 6 months: treatment of nausea and vomiting induced by chemotherapy;
- In children ≥ 1 month: prevention and treatment of postoperative nausea and vomiting (injectable only).
Dosage of Ondansetron
a) Control of nausea and vomiting induced by chemotherapy and cytotoxic radiotherapy in adults:
– Emetogenic chemotherapy and radiotherapy: 8 mg slow intravenous injection or rapid intravenous perfusion (15 min) immediately before or 8 mg oral 1-2 h before, followed by 8 mg oral 12 h after; max. 5 days.
Protection against delayed or prolonged emesis after 1 to 24 hours: oral 8 mg/12 h, 5 days after a course of treatment.
– Highly emetogenic chemotherapy: select one of the following guidelines:
1) Single dose of 8 mg per 15-minute intravenous perfusion immediately prior to chemotherapy; doses > 8 mg and max. 16 mg should be perfused for 15 min (do not administer doses >16 mg for dose-dependent increase in risk of prolongation of the QT interval).
2) Single dose of 8 mg per 15-minute intravenous perfusion, immediately before chemotherapy, followed by 2 IV doses of 8 mg spaced 4 hours apart, or by constant perfusion of 1 mg/h for 24 hours.
Efficacy of ondansetron in highly emetogenic chemotherapy can be enhanced by adding a single dose IV of 20 mg dexamethasone sodium phosphate prior to chemotherapy.
Protection against delayed or prolonged emesis after 1 to 24 hours: 8 mg/12 orally, 5 days after a course of treatment.
b) Treatment of nausea and vomiting induced by chemotherapy in children ≥ 6 months – adolescents, to be administered immediately before.
Calculation based on body area or body weight (calculation of total dose/day according to body weight > calculation of total dose/day according to body area):
– According to body area: < 0.6 m 2 , single intravenous (IV) dose 5 mg/m 2 and after 12 h 2 mg oral, can be extended up to 5 days with 2 mg/12 h oral; ≥ 0.6 m 2 , single IV dose 5 mg/m 2 and after 12 h 4 mg oral, can be extended up to 5 days with 4 mg/12 h oral; >1.2 m 2 , single IV dose 5 mg/m 2 and after 12 h 8 mg oral, can be extended up to 5 days with 8 mg/12 h oral.
– Depending on body weight: ≤ 10 kg, up to 3 intravenous (IV) doses of 0.15 mg/kg can be administered in 4-hour intervals, after 12 hours it can be started orally and extended up to 5 days with 2 mg/12 h oral; > 10 kg, up to 3 IV doses of 0.15 mg/kg in 4-hour intervals, after 12 hours it can be started orally and extended up to 5 days with 4 mg/12 h oral.
Dosage IV max. 8 mg. Daily dose max. 32 mg.
c) Prevention of postoperative nausea and vomiting.
Adults: single dose 4 mg intravenous (IV) perfusion slow to induce anaesthesia, or single dose 16 mg oral 1 h before anaesthesia (alternative: 8 mg oral 1 h before anaesthesia followed by 2 additional doses of 8 mg at 8 h intervals).
Children ≥ 1 month – adolescents: single dose 0.1 mg/kg IV slow (> 30 sec), max. 4 mg, before, during or after induction of general anesthesia.
d) Treatment of postoperative nausea and vomiting.
Adults: single dose 4 mg slow intravenous (IV) perfusion.
Children ≥ 1 month – adolescents: single dose 0.1 mg/kg Slow IV (> 30 sec), max. 4 mg.
Moderate-severe liver failure: max. 8 mg/day.
Mode of administration of Ondansetron
Lyophilizers are placed over the upper part of the tongue.
Contraindications of Ondansetron
Hypersensitivity to the active substance or other 5-HT3 antagonists; concomitant use with apomorphine.
Warnings and Cautions with Ondansetron
Limited experience in the elderly for the prevention and treatment of postoperative nausea and vomiting; in the elderly the initial dose IV max. 8 mg.
Moderate-severe liver failure (max. 8 mg/day); risk of hypersensitivity reactions.
Avoid in patients with congenital prolonged QT segment syndrome. Caution in patients who may develop prolonged QTc intervals (including patients with electrolyte abnormalities, CHF, bradyarrhythmias, or concomitant treatment with medications that prolong the QT interval or produce electrolyte abnormalities).
Correct hypokalemia and hypomagnesemia before starting treatment. Risk of serotonergic syndrome (altered mental state, autonomic instability, neuromuscular abnormalities) after concomitant use with other serotonergic drugs (SSRI, IRSNA).
May mask occult bleeding in patients undergoing adenotonsillar surgery (monitor); in patients with signs of subacute bowel obstruction, monitor after administration. Children with concomitant treatment with chemotherapy hepatotoxic agents should be monitored for impaired liver function;
In children, no data on: prevention of delayed or prolonged chemotherapy-induced nausea and vomiting or nausea and vomiting induced by radiotherapy.
Caution in moderate-severe liver failure; max. 8 mg/day.
Interactions with Ondansetron
- Contraindicated with: apomorphine.
- Plasma concentrations reduced by: CYP3A4 inducers (phenytoin, carbamazepine, rifampicin).
- Risk of serotonergic syndrome (altered mental state, autonomic instability, neuromuscular anomalies) with: serotonergic drugs (SSRI, SNRI).
- May reduce analgesic effect of: tramadol (small studies).
- Further extension of QT interval with: QT prolonging drugs.
- Increased risk of arrhythmias with: cardiotoxic drugs (e.g. anthracyclines such as doxorubicin, daunorubicin or trastuzumab; antibiotics such as erythromycin or ketoconazole; antiarrhythmics such as amiodarone and beta blockers such as atenolol or timolol).
Pregnancy and Ondansetron
Not recommended. The safety of ondansetron for use in human pregnancy has not been established.
Studies have shown that ondansetron passes into milk in lactating animals.
It is therefore recommended that lactating mothers do not breast-feed their children if they are taking ondansetron.
Effects on driving ability
In psychomotor testing, ondansetron does not affect the ability to drive and use machinery nor does it cause sedation.
No detrimental effects on these activities are seen from ondansetron pharmacology.
Adverse reactions and side effects of Ondansetron
Headache; hot flashes; constipation; local reactions instead of intravenous (IV) injection.
⭐⭐⭐⭐⭐ VIDEO OF ONDANSETRON/ZOFRAN (DRUG)
Source: The content of this active ingredient has been written taking into account the clinical and molecular information of all medicines authorised and marketed in the United States under the Unique Ingredient Identifier (UNII) by the Substance Registration System (SRS) of the Food and Drug Administration (FDA) and the United States Pharmacopeia (USP).
In order to know in detail the information authorized by the FDA for each drug, you should consult the corresponding medication guide authorized by the FDA.