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Zofran
Injection
Flexi-amp Ampoules
Ondansetron
QUALITATIVE AND QUANTITATIVE COMPOSITION
Each 1 ml of aqueous solution contains 2 mg ondansetron as hydrochloride dihydrate.
PHARMACEUTICAL FORM
A clear, colourless, sterile solution for injection or infusion.
CLINICAL PARTICULARS
Indications
ZOFRAN injection is indicated for the management of nausea and vomiting induced by cytotoxic chemotherapy and radiotherapy.
ZOFRAN is also indicated for the prevention and treatment of post-operative nausea and vomiting.
Dosage and Administration
ZOFRAN is available for oral and parenteral use to allow the route of administration and dosing to he flexible.
CHEMOTHERAPY AND RADIOTHERAPY INDUCED NAUSEA AND VOMITING
Adults
The emetogenic potential of cancer treatment varies according to the doses and combinations of chemotherapy and radiotherapy regimens used.
The dose range of ZOFRAN Injection is 8 to 32 mg a day and selected as shown below:
EMETOGENIC CHEMOTHERAPY AND RADIOTHERAPY
The recommended i.v. or i.m. dose of ondansetron is 8 mg administered as a slow injection immediately before treatment.
Oral treatment is recommended to protect against delayed or prolonged emesis after the first 24 h.
HIGHLY EMETOGENIC CHEMOTHERAPY
For patients receiving highly emetogenic chemotherapy, e.g. high-dose cisplatin, ZOFRAN may be administered as a single 8 mg i.v. or i.m. dose immediately before chemotherapy. Doses of greater than 8 mg and up to 32 mg of ondansetron may only be given by i.v. infusion diluted in 50 to 100 ml of saline or other compatible infusion fluid (see Instructions for Use and Handling) and infused over not less than 15 mins.
Alternatively a dose of 8 mg of ondansetron may be administered by slow i.v. or i.m. injection immediately before chemotherapy, followed by two further i.v. or i.m. doses of 8 mg 2 to 4 h apart, or by a constant infusion of 1 mg/h for up to 24 h.
The selection of dose regimen should be determined by the severity of the emetogenic challenge.
The efficacy of ZOFRAN in highly emetogenic chemotherapy may be enhanced by the addition of a single i.v. dose of dexamethasone sodium phosphate, 20 mg administered prior to chemotherapy.
Oral treatment is recommended to protect against delayed or prolonged emesis after the first 24 h.
Children
ZOFRAN may be administered as a single intravenous dose of 5 mg/m2 immediately before chemotherapy, followed by an oral dose twelve hours later. Oral therapy should be continued for up to 5 days after a course of treatment.
Elderly
ZOFRAN is well tolerated by patients over 65 years and no alteration of dosage, dosing frequency or route of administration are required.
POST-OPERATIVE NAUSEA AND VOMITING
• Adults
For prevention of post-operative nausea and vomiting, the recommended dose of ondansetron injection is a single dose of 4 mg by i.m. or slow i.v. injection administered at the induction of anaesthesia.
For treatment of established post-operative nausea and vomiting a single dose of 4 mg given by i.m. or slow i.v. injection is recommended.
• Children
For prevention of PONV in paediatric patients having surgery performed under general anaesthesia, ondansetron may be administered by slow i.v. injection at a dose of 0.1 mg/kg up to a maximum of 4 mg either prior to, at or after induction of anaesthesia.
For treatment of established PONV in paediatric patients, ondansetron may be administered by slow i.v. injection at a dose of 0.1 mg/kg up to a maximum of 4 mg.
• Elderly
There is limited experience in the use of ZOFRAN in the prevention and treatment of post-operative nausea and vomiting in the elderly, however ZOFRAN is well tolerated in patients over 65 years receiving chemotherapy.
• Patients with Renal Impairment
No alteration of daily dosage or frequency of dosing, or route of administration are required.
• Hepatic Impairment
Clearance of ondansetron is significantly reduced and serum half-life significantly prolonged in subjects with moderate or severe impairment of hepatic function. In such patients a total daily dose of 8 mg should not be exceeded.
• Patients with Poor Sparteine/Debrisoquine Metabolism
The elimination half-life of ondansetron is not altered in subjects classified as poor metabolisers of sparteine and debrisoquine. Consequently in such patients repeat dosing will give drug exposure levels no different from those of the general population. No alteration of daily dosage or frequency of dosing are required.
Contraindications
Hypersensitivity to any component of the preparation.
Warnings and Precautions
Hypersensitivity reactions have been reported in patients who have exhibited hypersensitivity to other selective 5HT3 receptor antagonists.
Very rarely and predominantly with intravenous ondansetron, transient ECG changes including QT interval prolongation have been reported.
As ZOFRAN is known to increase large bowel transit time, patients with signs of subacute intestinal obstruction should be monitored following administration.
Interactions
There is no evidence that ZOFRAN either induces or inhibits the metabolism of other drugs commonly coadministered with it. Specific studies have shown that there are no pharmacokinetic interactions when ZOFRAN is administered with alcohol, temazepam, frusemide, tramadol or propofol.
Ondansetron is metabolised by multiple hepatic cytochrome P-450 enzymes: CYP3A4, CYP2D6 and CYP1A2. Due to the multiplicity of metabolic enzymes capable of metabolising ondansetron, enzyme inhibition or reduced activity of one enzyme (e.g. CYP2D6 genetic deficiency) is normally compensated by other enzymes and should result in little or no significant change in overall ondansetron clearance or dose requirement.
Phenytoin, Carbamazepine and Rifampicin
In patients treated with potent inducers of CYP3A4 (i.e. phenytoin, Carbamazepine, and rifampicin), the oral clearance of ondansetron was increased and ondansetron blood concentrations were decreased.
Tramadol
Data from small studies indicate that ondansetron may reduce the analgesic effect of tramadol.
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