BMA Concise Guide to Medicine & Drugs

Carbamazepine

Brand names Carbagen SR, Epimaz, Tegretol, Tegretol Retard

Used in the following combined preparations None

QUICK REFERENCE

Drug group Anticonvulsant drug

Overdose danger rating Medium

Dependence rating Low

Prescription needed Yes

Available as generic Yes

GENERAL INFORMATION

Carbamazepine is used to treat several forms of epilepsy as it reduces the likelihood of seizures caused by abnormal nerve signals in the brain.

Carbamazepine is also prescribed to relieve the intermittent severe pain caused by irritation of the cranial nerves in trigeminal neuralgia. It is also prescribed to stabilize mood in bipolar disorder (manic depression), to reduce urine output in diabetes insipidus, and to relieve pain in diabetic neuropathy.

In order to avoid side effects, carbamazepine therapy is usually commenced at a low dose and is gradually increased. It is recommended that patients stick to the same brand of carbamazepine prescribed.

INFORMATION FOR USERS

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

How taken/used Tablets, chewable tablets, liquid, suppositories.

Frequency and timing of doses 1–2 x daily.

Adult dosage range Epilepsy 100–2,000mg daily (low starting dose that is slowly increased every 2 weeks). Pain relief 100–1,600mg daily. Psychiatric disorders 400–1,600mg daily.

Onset of effect Within 4 hours.

Duration of action 12–24 hours.

Diet advice None.

Storage Keep in original container at room temperature out of the reach of children.

Missed dose Take as soon as you remember. If your next dose is due within 2 hours, take a single dose now and skip the next.

Stopping the drug Do not stop the drug without consulting your doctor; symptoms may recur.

Exceeding the dose An occasional unintentional extra dose is unlikely to cause problems. Large overdoses may cause tremor, seizures, and coma. Notify your doctor.

POSSIBLE ADVERSE EFFECTS

Most people experience very few adverse effects with carbamazepine, although when blood levels get too high, adverse effects are common and the dose may need to be reduced. Dizziness, unsteadiness, drowsiness, nausea, and loss of appetite are common side effects. Blurred vision is also common; it should be reported to your doctor in all cases. Rarer side effects include jaundice and swelling of the ankles, which should also be notified to your doctor. If you develop a sore throat, hoarseness, rash, fever, or abnormal bruising, stop taking the drug and contact your doctor immediately.

INTERACTIONS

General note Many drugs may increase or reduce the effects of carbamazepine. Discuss with your doctor or pharmacist before taking other medications.

Other antiepileptic drugs Complex and variable interactions can occur between these drugs and carbamazepine.

Contraceptive pill Carbamazepine may reduce the effectiveness of the contraceptive pill. Discuss this with your doctor.

SPECIAL PRECAUTIONS

Be sure to tell your doctor if:

· You have a long-term liver or kidney problem.

· You have heart problems.

· You have had blood problems with other drugs.

· You are taking other medicines.

Pregnancy Avoid if possible. Associated with abnormalities in the unborn baby. Folic acid supplements should be taken before and during pregnancy. Discuss with your doctor.

Breast-feeding The drug passes into the breast milk and can affect the baby. Discuss with your doctor.

Infants and children Reduced dose necessary.

Over 60 May cause confused or agitated behaviour in the elderly. Reduced dose may be necessary.

Driving and hazardous work Discuss with your doctor. Your underlying condition, as well as the possibility of reduced alertness while taking carbamazepine, may make such activities inadvisable.

Alcohol Avoid. Alcohol may increase the sedative effects of this drug.

PROLONGED USE

There is a slight risk of changes in liver function or of skin or blood abnormalities occurring during prolonged use.

Monitoring Periodic blood tests are usually performed to monitor levels of the drug, blood cell counts, and liver and kidney function.