Carbamazepine

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Carbamazepine is one of the most important remedies for convulsions (epilepsy). It has long been known as an active ingredient and is often prescribed due to many years of experience. However, carbamazepine can interact with many other drugs. Therefore, patients must be very well looked after by a doctor and pharmacist during treatment. Here you can read everything you need to know about carbamazepine.

This is how carbamazepine works

Mechanism of action

The human nervous system is activated or inhibited by certain messenger substances (neurotransmitters). Normally, these messenger substances are released according to external circumstances and ensure that the body reacts appropriately to various situations such as injuries, stress or rest.

This controlled equilibrium is disturbed in diseases of the nervous system. A genetic predisposition or injuries to the brain can increase the excitement or reduce the inhibition. The result: the nervous system of the brain is overexcitable, and epileptic seizures can occur.

As an anti-epileptic, carbamazepine lowers the over-excitability of nerve cells by blocking certain ion channels, thus reducing the risk of an epileptic seizure.

Carbamazepine uptake, breakdown and excretion

Carbamazepine is absorbed from the intestine into the blood relatively slowly but completely. The effect occurs after four to 16 hours. It is then broken down in the liver and excreted via the kidneys (with the urine) and the intestines (with the stool).

When is carbamazepine used?

The areas of application (indications) of carbamazepine are:

Seizures (epilepsy)
Nerve damage caused by diabetes (diabetic neuropathy)

This is how carbamazepine is used

Carbamazepine is used in the form of tablets, sustained-release tablets (sustained release tablets), and juices. The medication is usually taken with plenty of fluids (preferably a large glass of water) with or after a meal. The carbamazepine dosage is determined individually for each patient. Usually one starts with 200 milligrams daily; the dose can then be increased slowly up to 1200 milligrams. The doctor should check the success of the treatment intensively, especially in the initial phase, in order to find the right dose together with the patient.

Children, adolescents, the elderly, patients with cardiovascular diseases and those with kidney or liver problems receive a lower dose.

Patients should have a genetic test prior to carbamazepine treatment, as there is ample evidence that certain side effects are more likely to occur with certain genetic changes. If these have been ruled out beforehand, the risk of some side effects is significantly lower.

What side effects does carbamazepine have?

Very often, i.e. in more than ten percent of those treated, carbamazepine can cause side effects such as dizziness and tiredness. Frequently (in one to ten percent of patients) there are allergic reactions, changes in the blood count and liver function, reduction in blood salts and gastrointestinal problems. Occasionally, in less than one percent of those treated, carbamazepine causes involuntary movements, kidney or heart dysfunction, headache and confusion. Visual disturbances and speech disorders develop even more rarely.

What should be considered when taking carbamazepine?

Application limitations

Carbamazepine may only be used after a strict risk-benefit assessment, if there are blood formation disorders, a disturbed sodium metabolism or cardiac, kidney or liver dysfunction.

Contraindications

Carbamazepine must not be taken if patients have bone marrow damage, cardiac dysfunction or a certain blood count disorder (acute intermittent porphyria).

Furthermore, simultaneous use with voriconazole (against fungal diseases) and MAO inhibitors (against Parkinson's disease or depression) is expressly discouraged.

Age restrictions

In children under six years of age, the active ingredient carbamazepine may only be used after carefully weighing the risks and benefits.

Interactions

The active ingredient carbamazepine is very susceptible to interactions with other drugs.

It reduces the effects of the following drugs:

other anti-epileptic drugs
Benzodiazepines (for insomnia)
Tetracyclines (antibiotics)
Indinavir (for HIV infection)
certain blood thinners (warfarin, phenprocoumon)
Theophylline (for asthma)
Digoxin (for heart dysfunction)
Thyroid hormones (L-thyroxine)

The following drugs reduce the effect of carbamazepine:

Theophylline (for asthma)
Doxorubicin and cisplatin (for cancer)

Effects and side effects of carbamazepine are intensified by the following substances:

certain antibiotics (erythromycin, clarithromycin)
Isoniazid (for tuberculosis)
Verapamil, diltiazem (for irregular heartbeat)
Cimetidine (for heartburn etc.)

pregnancy and breast feeding period

The active ingredient carbamazepine can harm the unborn child, which is why pregnant women with epilepsy should be switched to another anti-epileptic drug (lamotrigine) if possible. If a safe transition is not possible, the carbamazepine dosage should be kept as low as possible during pregnancy.

It can be used during breastfeeding.

Driving and using machines

Carbamazepine can cause side effects such as dizziness, drowsiness, and tiredness. Therefore, experts advise against actively driving or operating heavy machinery during carbamazepine therapy.

This is especially true in combination with alcohol, as carbamazepine reduces alcohol tolerance.

How to get drugs with carbamazepine

Carbamazepine is one of the most potent active ingredients. The effects and side effects must be regularly recorded and checked by a doctor. That is why you can only get drugs with carbamazepine with a doctor's prescription in the pharmacy.

Since when is carbamazepine known?

Carbamazepine has been known for a very long time. The drug has now been chemically optimized; the new active ingredient oxcarbazepine is said to have fewer side effects and interactions than the "older" carbamazepine. However, there is not a lot of data on this yet, which is why carbamzepine is still being prescribed more frequently. It remains to be seen whether the “improved” active ingredient will catch on.

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