Carbamazepine Health Article

Definition

Carbamazepine is an antiepileptic drug used to reduce or suppress seizures. The medication is also commonly prescribed to relieve certain neurogenic pain such as trigeminal neuralgia. This drug decreases abnormal electrical impulses through nerve cell pathways by inhibiting the activity of sodium channels in neurons. Consequently, it blocks the repetitive impulses that trigger seizures. In the United States, brand names for carbamazepine include Tegretol, Carbatrol, and Epitol. This medication is classified into the following categories: anticonvulsant, antimanic, and antineuralgic.

Purpose

Due to its high efficacy, carbamazepine is in many cases a first-line treatment for epilepsy, and is also frequently prescribed to treat acute neuralgias such as trigeminal neuralgia. Sometimes the drug is also used to improve bipolar disorder symptoms, especially during the manic phase of this disease.

Description

Carbamazepine is a lipid-soluble substance metabolized in the liver by enzymes of the P-450 family and therefore, its chronic administration may induce liver toxicity, especially in patients with reduced liver function. In contrast, persons whose P-450 enzymes are very efficient and metabolize the drug rapidly tend to have decreased carbamazepine half-life and therefore, reduced efficacy of the medication. The body slowly absorbs carbamazepine and the drug easily passes through the blood-brain barrier. It is rapidly transported into the central nervous system (CNS), where it exerts a depressant effect.

Recommended dosage

For treatment of seizures, the usual initial dose of carbamazepine for adults and children over 12 years of age is 200 milligrams, taken twice daily. The prescribing physician may increase the dosage in weekly intervals until optimum seizure control is achieved. Dosages generally do not exceed a range of 1000–1200 milligrams (mg) per day. For the treatment of trigeminal neuralgia, daily dosages usually range from 800–1200 mg per day during the stage of acute pain and 400–800 mg per day for preventative therapy.

Precautions

The ingestion of alcoholic drinks during carbamazepine therapy is contraindicated because both substances may potentiate (increase) the effects of the other. Other depressants of the central nervous system such as antihistamines, analgesic drugs, muscle relaxants, and tranquilizers, are also potentiated when used with carbamazepine or other antiepileptic medications. Diabetic patients should be monitored during the administration of this drug since it interferes with glucose blood levels. The drug should not be taken during pregnancy due to the absence of safety clinical studies for pregnant women. Tests in animals have shown that carbamazepine causes developmental defects in embryos when administered in high doses. As the drug is found in breast milk, the use of this medication is also contraindicated during breast-feeding. Carbamazepine may interfere with several biomarkers used in medical laboratory tests, and persons taking the medication should report its intake before blood or urine samples are collected for analysis.

Side effects

The intensity of side effects (or adverse effects) of carbamazepine is dose-dependant. Among the mild adverse effects observed during chronic administration of this medication are drowsiness, vertigo, fatigue, blurred vision, gastritis, constipation, aching muscles or joints, skin sensitivity to solar radiation, loss of appetite, and dry mouth. In most patients, these side effects are mild and tend to decrease in intensity or to completely disappear within a few days of treatment. However, if they are particularly intense or do persist for two or more weeks they should be reported to the physician.

Nevertheless, elderly patients or patients exhibiting one or more severe symptoms in association with carbamazepine intake such as chest pain, blurred vision, mental confusion or hallucinations, numbness, tachycardia, depression or marked mood changes, urinary retention or excessive diuresis, peripheral edema, severe diarrhea or vomiting, should report such symptoms to their physicians as soon as possible.

Moreover, immediate medical attention may be required in the presence of one or more of the following adverse effects: presence of blood in the urine or urine with a dark color, black tarry stools or pale stools, unusual bleeding or bruising, skin rashes, ulcers or white spots in the mouth or lips, chills and fever, shallow or uneasy breathing or wheezing chest, jaundice, arrhythmia, sudden blood pressure fall or unusual high blood pressure, cough and/or sore throat. These side effects could indicate the presence of a potentially serious blood disorder.