Carbamazepine | Laboratory research

Carbamazepine (Finlepsin, Tegretol) is an antiepileptic and psychotropic drug. Carbamazepine concentrations in the blood need to be monitored regularly and maintained within the therapeutic dose to achieve a therapeutic effect and avoid side effects.

Carbamazepine blocks the sodium channels of hyperactive nerve cells, reduces the effects of excitatory neurotransmitters (glutamate, aspartate), enhances inhibitory (GABAergic) processes, and interacts with the adenosine central receptor.

In the digestive tract it is absorbed slowly but almost completely, food does not affect the speed and quality of its absorption. When taken orally, its maximum concentration in the blood is reached after 12 hours. Penetrates into saliva, cerebrospinal fluid, breast milk and crosses the placental barrier. It is metabolized in the liver to form several metabolites. The half-life of carbamazepine in adults is 14-65 hours (long-term use - 8-29 hours), and in children - 8-19 hours. 70% of the drug is excreted by the kidneys and 30% by the intestines. In children, the release of carbamazepine is accelerated.

Difficulties in maintaining a certain concentration of carbamazepine are related to individual characteristics - the level of drug absorption in the digestive tract, the functional state of the liver, the protein content in the blood (binds to medication).

The dosage of carbamazepine and the method of its administration are determined and regulated by the doctor, individually for each patient.

Thanks to laboratory control of carbamazepine content in the blood, it is possible to maintain the concentration of the drug in the therapeutic window, allowing you to get the maximum effect from its use and avoid overdose and side effects.

When should we test for carbamazepine?

Blood carbamazepine is prescribed in the following cases:

• Constant use of the drug (should be determined once every three months);
• Selecting the effective dose when prescribing the drug;
• Dose change of the drug (after 2-3 weeks);
• Prescribing additional antiepileptic drug;
• Suspicion of side effects;
• Decreased effectiveness of the drug (appearance of epileptic seizures);
• Pregnancy (should be determined once every 2-4 weeks).

The test is prescribed when there are side effects or complications in the face. Side effects that may occur at any dose but are associated with higher concentrations include:

• Dizziness;
• Uncoordinated movement;
• Drowsiness;
• Blurred or double vision;
• Involuntary movement of the eyeball back and forth.

Other side effects may include:

• Skin rash;
• Itchy skin;
• Nausea;
• Diarrhea;
• Constipation;
• headache;
• Confusion.

Carbamazepine can also cause liver dysfunction, low sodium levels, a decrease in white blood cells, or an increase in eosinophils (a type of white blood cell). In some cases, it may be necessary to use another medication because of the severity of the side effects.

How to prepare for the test?

No special preparation is required for the test.

Ask your doctor at what time the test is recommended, as often, the recommended time for testing coincides with the time when the blood carbazepine level is low (before taking the next dose).

Research material

Venous blood

Possible interpretation of the results

In most people, the body responds to the drug within the therapeutic range without undue side effects; However, the body's response is individual. Some people experience seizures, mood swings, or other side effects below the therapeutic range, while some people experience excessive side effects at the upper end of the therapeutic range.

Elevated levels of carbamazepine in the blood indicate that the patient is taking an overdose of the medication or that the patient is taking medications with carbamazepine that affect his or her concentration.

Generally, if the carbamazepine test results are in the therapeutic range and the person does not experience recurrent seizures, mood swings, or neuralgia and has no significant side effects, then the carbamazepine dose is considered adequate.

Resources

https://spravochnik.synevo.ua/ru/lekarstvenniy-monitoring/carbamazepine.html

https://www.synevo.ro/shop/carbamazepina/

https://www.testing.com/tests/carbamazepine/