Ondansetron hydrochloride dihydrate.
Film-coated tablet: Each film-coated tablet contains: Ondansetron (as hydrochloride dihydrate) 4 mg or 8 mg.
Solution for injection: Each mL contains: Ondansetron (as hydrochloride dihydrate) 2 mg.
Pharmacology: Pharmacokinetics: Peak plasma concentrations of ondansetron occur about 1.5 hours after an oral dose of 8 mg, and about 6 hours after a rectal dose. The absolute bioavailability is about 60%, mainly because of hepatic first-pass metabolism. In elderly subjects, bioavailability may be somewhat higher (65%) and clearance lower, presumably due to reduced hepatic first-pass metabolism. Ondansetron is extensively distributed in the body; about 70 to 75% of the drug in plasma is protein bound. It is metabolized in the liver through multiple enzymatic pathways; ondansetron is a substrate for cytochrome P450 isoenzymes, primarily CYP3A4, but also CYP1A2 and CYP2D6. Less than 5% of a dose is excreted unchanged in the urine. The terminal elimination half-life is about 3 hours after oral or parenteral doses, and about 6 hours after rectal use. The terminal elimination half-life is prolonged to about 5 hours in the elderly and in those with renal impairment. These differences are not considered sufficient to warrant dosage adjustment. However, in patients with severe hepatic impairment, bioavailability may approach 100% and clearance is markedly reduced, with elimination half-lives of 15 to 32 hours; dosage restriction is advisable. In general, children have a higher clearance than adults, although age-related reductions in clearance have also been reported, with younger children having lower clearances. Use of weight-based doses compensates for these changes and normalizes exposure in paediatric patients.
Ondansetron is a 5-HT3 antagonist (5 HT3-receptor antagonist) with antiemetic activity. It is used in the management of nausea and vomiting induced by cytotoxic chemotherapy and radiotherapy. It is also used in the prevention and treatment of post-operative nausea and vomiting.
Preventing acute emesis with less emetogenic chemotherapy and/or radiotherapy: 8 mg can be given orally up to 2 hours before treatment followed by 8 mg 8 to 12 hours later.
Preventing acute emesis with highly emetogenic chemotherapy: 8 mg by slow intravenous or intramuscular injection immediately before treatment, either followed by a continuous intravenous infusion of 1 mg/hour for up to 24 hours, or by a further two doses of 8 mg two to four hours apart.
Prevent postoperative nausea and vomiting: Film-coated tablet: Adults may be given 16 mg orally an hour before anaesthesia or 8 mg orally an hour before anaesthesia followed by 2 further doses of 8 mg at 8-hour intervals.
Solution for injection: Adults may be given single dose of 4 mg by intramuscular or slow intravenous injection at induction of anaesthesia.
Treatment of postoperative nausea and vomiting: Solution for injection: A single 4 mg dose by intramuscular or slow intravenous injection is recommended.
Patients with hepatic impairment: Should not exceed 8 mg daily in patients with moderate or severe hepatic impairment.
Hypersensitivity to Ondansetron or to any components of the product.
Ondansetron should not be used during pregnancy, especially during the first trimester. Also, ondansetron should not be given to nursing mothers. Ondansetron may be given to pregnant or lactating women if the expected benefit to the patient outweighs any possible risk. They should be used with care in patients with signs of subacute intestinal obstruction or ileus. Ondansetron should be given in reduced doses to patients with moderate to severe hepatic impairment.
Ondansetron should not be used during pregnancy, especially during the first trimester. Also, ondansetron should not be given to nursing mothers. Ondansetron may be given to pregnant or lactating women if the expected benefit to the patient outweighs any possible risk.
Ondansetron and other 5-HT3 antagonists may cause headache, a sensation of flushing or warmth, hiccups, and constipation. A transient rise in liver enzymes has occasionally occurred. There have been rare reports of immediate hypersensitivity reactions, including anaphylaxis. Chest pain, arrhythmias, hypotension, tachycardia, and bradycardia have been reported rarely. Rashes and urticaria have also occurred.
Ondansetron does not appear to induce or inhibit the cytochrome P450 isoenzyme system, but it is itself metabolised by multiple hepatic isoenzymes, including CYP3A4, CYP2D6, and CYP1A2. US licensed product information states that inducers or inhibitors of these isoenzymes may change the clearance and half-life of ondansetron, but that on the basis of available data, no dose adjustments are recommended. UK licensed product information states that enzyme inhibition of one isoenzyme is usually compensated for by other enzymes and should result in little or no significant change in overall ondansetron clearance or dose requirement. Potent inducers of CYP3A4, such as phenytoin, carbamazepine, and rifampicin, have been reported to increase ondansetron clearance and reduce ondansetron plasma concentrations. Because of the reports of transient ECG changes in some patients taking 5-HT3 antagonists, there is a theoretical need for caution if given with other drugs that prolong QT-interval; however, clinical evidence of a significant interaction seems to be mostly lacking.
Store at temperatures not exceeding 30°C.
Solution for injection: Protect from light.
A04AA01 - ondansetron ; Belongs to the class of serotonin (5HT3) antagonists. Used for the prevention of nausea and vomiting.
FC tab 4 mg x 12's. 8 mg x 12's. Soln for inj (amp) 2 mg/mL x 2 mL x 5's, 4 mL x 5's.