Avapritinib is used to treat a certain type of cancer of the stomach, bowel, or oesophagus that is caused by a certain defect in the gene called PDGFRA. It is used in individuals who cannot be treated with surgery or whose cancer has spread to other parts of the body.
This medicine may also be used to treat systemic mastocytosis (a rare disorder that causes too many build-ups of a type of white blood cell called mast cells in the body). It is used in individuals whose disease has spread to other parts of the body or has come back.
Take Avapritinib exactly as directed by your doctor or according to the instructions on the label. Do not take more or less than instructed by your doctor.
Take it on an empty stomach, at least 1 hour before or 2 hours after a meal. Try to take it at the same time each day.
Swallow the tablet whole with a glass of water.
If you vomit after taking a dose of this medicine, do not repeat the dose. Return to your normal dosing schedule.
The dose of this medicine will be decided by your doctor. Your doctor will advise you on the course of treatment depending on the type of your disease and response to the medication.
Avapritinib must be taken regularly for it to be effective. Continue taking this medicine even when you feel better. Do not stop taking it unless instructed by the doctor.
Take the missed dose as soon as you remember. If it is almost time for your next dose or if it is less than 8 hours until your next dose, skip the missed dose and return to your normal dosing schedule.
DO NOT double a dose under any circumstances.
If you often forget to take your medicine, let your doctor and pharmacist know.
Do not breastfeed while you are being treated with Avapritinib and for at least 2 weeks after stopping the treatment.
Inform your doctor if you have the following conditions:
- have or have had bleeding problems
- lower than normal platelet count in the blood
- history of vascular aneurysm (bulging and weakening of a blood vessel wall) or bleeding in the brain within the previous year
- heart rhythm problems
- severe kidney disease
- severe liver disease
Let your doctor know if you are pregnant. Avapritinib may cause harm to your unborn child.
It is important that you do not get pregnant while being treated with this medicine. You must use proven birth control methods while taking Avapritinib and for 6 weeks after your last dose. You may wish to discuss birth control methods with your doctor or pharmacist.
Men with female partners who may become pregnant must use proven birth control methods during treatment with this medicine and for 6 weeks after the last dose.
Why is it important to keep my appointments with the doctor?
Keep your appointments with your doctor. Your doctor needs to monitor your condition and check your response to the medication regularly.
- Pregnancy tests must be done before treatment to know if this medicine is suited for you to take.
- If you are taking this medicine for cancer of the digestive tract, screening and assessment for an alteration in your gene may be needed to check the appropriateness of Avapritinib therapy.
- Routine tests (e.g. liver function, complete blood count) may be done while you are being treated with this medicine. Your doctor will advise you about how often you need to have these tests.
- Regular monitoring of signs and symptoms of mental changes and bleeding in the brain may also be needed.
Avapritinib may affect your ability to concentrate and react. If affected, do not drive or take part in any activity in which you need to be alert.
This medicine may also make your skin more sensitive to sunlight. Apply sunscreen when going outdoors and avoid prolonged exposure to sunlight and UV lamps.
Other side effects include any of the following: headache, dizziness with or without sensations of spinning, drowsiness, nausea, vomiting, diarrhoea, constipation, stomach pain, stomach wind, changes in taste, difficulty swallowing, back pain, changes in hair colour, hair loss, weight gain or loss, cough, stuffy nose, and difficulty sleeping.
Some side effects may need immediate medical help. Alert your doctor quickly if you experience any of the following:
- severe headache, vision problems, severe weakness on one side of the body
- forgetfulness, confusion, difficulty thinking, changes in mood or behaviour
- shortness of breath
- pass out bloody or black as tar stools and vomiting blood or ground coffee-like material
Inform your doctor if any of these side effects do not go away or are severe, or if you experience other side effects.
Inform your doctor and pharmacist if you are taking any of these medicines:
- medicines to treat fungal infection e.g. itraconazole, ketoconazole
- certain antibiotics e.g. erythromycin, clarithromycin, nafcillin
- medicines for HIV infection e.g. indinavir, ritonavir, efavirenz
- medicines for epilepsy (fits or seizures) e.g. carbamazepine, phenytoin, phenobarbital, primidone
- rifampicin (medicine to treat TB [lung infection known as tuberculosis])
- boceprevir (medicine for hepatitis C infection)
- conivaptan (medicine for low sodium level in the blood)
- modafinil (medicine for sleep disorders)
- St. John's wort (herbal medicine)
This list does not include all medicines that may interact with Avapritinib.
Always notify your doctor and pharmacist if you are taking any other medicines, including herbal tonics such as traditional Chinese medicines, supplements, and medicines that you buy without a prescription.
Avoid alcohol.
Avoid excessive consumption of grapefruit or grapefruit juice (more than 1 litre a day).
Store in a cool, dry place away from the reach of children.
Medicines must not be used past the expiry date.
As this is a cancer medicine, always return any unused or expired tablets to the clinic, hospital, or pharmacy for disposal. Do not throw it away in the household waste.
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