Product information
About Onzet
Onzet contains ondansetron, a medicine known as a 5HT3 receptor antagonist. Chemotherapy and radiotherapy can cause the release of a natural substance called serotonin (5HT), which can trigger nausea and vomiting. Onzet works by blocking this signal.
Onzet is used in adults to treat nausea and vomiting caused by chemotherapy and radiotherapy for cancer. It is also used to prevent and treat nausea and vomiting after an operation.
Onzet can also be used in children: for nausea and vomiting caused by chemotherapy from 6 months of age, and after an operation from 1 month of age (injection). Onzet injection is given by a doctor or nurse.
How to use
Use Onzet exactly as your doctor has told you. The dose depends on your treatment.
- Chemotherapy or radiotherapy, tablets or syrup: 8 mg (one tablet or 10 mL of syrup) taken 1 to 2 hours before treatment, then 8 mg every 12 hours for up to 5 days.
- Chemotherapy or radiotherapy, injection: 8 mg given slowly into a vein by a doctor or nurse just before treatment, usually followed by 8 mg by mouth every 12 hours.
- To prevent nausea and vomiting after an operation, tablets: 16 mg taken one hour before the anaesthetic. Injection: 4 mg given by a doctor or nurse when the anaesthetic starts.
- To treat nausea and vomiting after an operation: 4 mg given by injection into a muscle or slowly into a vein by a doctor or nurse.
- Children: the doctor works out the dose based on the child's size or weight.
A single injection dose of more than 16 mg must not be given. Older people over 75 years and people with liver problems may need a lower dose.
Composition
- Tablets
- Each tablet contains ondansetron 8 mg.
- Oral suspension
- Each 5 mL contains ondansetron 4 mg.
- Injection
- Each mL contains ondansetron 2 mg (8 mg in 4 mL and 4 mg in 2 mL).
- Pack sizes
- Tablets 8 mg; oral suspension 4 mg/5 mL; injection 8 mg/4 mL and 4 mg/2 mL ampoules.
Side effects and warnings
Like all medicines, Onzet can cause side effects, although not everybody gets them. The most common are headache, a feeling of warmth or flushing, constipation, and reactions where the injection is given.
- Do not use Onzet if you are allergic to ondansetron or similar medicines (such as granisetron), or if you are taking apomorphine (used for Parkinson's disease), as together they can cause a severe drop in blood pressure.
- Onzet can affect the heart rhythm (QT prolongation). Tell your doctor if you have heart problems, an irregular heartbeat, or low potassium or magnesium levels in the blood.
- Tell your doctor if you take other medicines that affect serotonin, such as some antidepressants (SSRIs or SNRIs) or opioid painkillers, as serotonin syndrome has been reported.
- Onzet slows the movement of the bowel. Tell your doctor if you have signs of a bowel blockage or severe constipation.
- Onzet should not be used in the first three months of pregnancy. Do not breast-feed while using Onzet. If you are pregnant, may be pregnant or are breast-feeding, ask your doctor first.
Always read the patient information leaflet in the pack. If you have any questions, ask your doctor or pharmacist.