BMA Concise Guide to Medicine & Drugs

Imatinib

Brand name Glivec

Used in the following combined preparations None

QUICK REFERENCE

Drug group Anticancer drug

Overdose danger rating Medium

Dependence rating Low

Prescription needed Yes

Available as generic No

GENERAL INFORMATION

Imatinib is a member of a new class of anticancer drugs called tyrosine kinase inhibitors, which work by blocking a specific enzyme (tyrosine kinase) in certain cancer cells, thereby arresting their growth and replication. This targeted effect makes these drugs very specific, with relatively little effect on normal, noncancerous cells (unlike many older anticancer drugs). Imatinib is used principally against chronic myeloid leukaemia (CML) but may also be used to treat some other bone marrow cancers and some rare gastrointestinal tumours. It can be used alone or in combination with other anticancer drugs.

Imatinib generally produces fewer adverse effects than older anticancer drugs. However, it does not usually provide a long-term cure because the cancer cells eventually mutate to become resistant to its effects.

INFORMATION FOR USERS

Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Tablets.

Frequency and timing of doses 1 x daily with food, at the same time every day.

Adult dosage range 100–600mg daily.

Onset of effect The drug starts inhibiting the enzyme within hours but the effect on cancer cells may take days to weeks to become detectable.

Duration of action Several days.

Diet advice None.

Storage Store in original packaging below 30°C out of the reach of children.

Missed dose Take as soon as you remember that day. If you do not remember that day, omit the missed dose and take the next dose as scheduled. Do not double your next dose.

Stopping the drug Do not stop the drug without consulting your doctor because this may lead to a worsening of the underlying condition.

Exceeding the dose An occasional unintentional extra dose is unlikely to cause major problems. But if you notice any unusual symptoms or if a large overdose has been taken, notify your doctor.

POSSIBLE ADVERSE EFFECTS

Imatinib can cause a variety of adverse effects, commonly gastrointestinal ones such as nausea, vomiting, and diarrhoea. Headache, dizziness, lightheadedness, and muscle pain are also common. Discuss with your doctor if any of these effects are severe. Other common adverse effects include oedema (fluid build-up), which may cause rapid weight gain, and effects on the blood. The latter may cause bruising, bleeding, and signs of infection, such as fever, sore throat, mouth ulcers, and a rash, which should be reported to your doctor without delay. More rarely, there may be chest pain, palpitations, cough, jaundice, or severe abdominal pain; consult your doctor promptly if any of these symptoms occur.

INTERACTIONS

General note A wide range of drugs (including over-the-counter and herbal remedies) may affect levels of imatinib in the body and it is therefore important to check with your doctor or pharmacist before taking any new medication or remedy.

Thyroxine Imatinib can increase the breakdown of thyroxine so the thyroxine dose may need adjustment.

Warfarin Imatinib may affect the level of warfarin; this may require adjustment of the warfarin dose or you may be switched to heparin.

SPECIAL PRECAUTIONS

Be sure to tell your doctor if:

· You have liver, kidney, or heart problems.

· You have had your thyroid gland removed and are taking thyroxine.

· You are taking other medicines.

Pregnancy Safety not established. Discuss with your doctor.

Breast-feeding Not recommended.

Infants and children Used only by specialist children’s doctors.

Over 60 No special problems.

Driving and hazardous work Avoid such activities until you have learned how the drug affects you. It may sometimes cause dizziness or blurred vision.

Alcohol No special problems.

PROLONGED USE

Imatinib tends to produce fewer adverse effects than many other anticancer drugs when used long-term but the cancer cells may become resistant to the drug’s effects, in which case treatment will be stopped.

Monitoring Regular monitoring is carried out to check your blood count and the function of organs such as the liver and kidney. Blood tests are also performed to monitor the response of the cancer to imatinib.