Carbamazepine

Carbamazepine - Use | Dose | Effects

Carbamazepine is a drug from the group of antiepileptic drugs and is used to treat epilepsy and neuropathy (usually the neuropathy which affects the trigeminal nerve responsible for transmitting sensory information from the face to the brain, so-called trigeminal neuropathy). The mechanism of action of this drug has not been fully elucidated. So far it is known that this drug inhibits neuronal discharges and reduces the propagation of excitatory impulses.

Carbamazepine is effective in the treatment of partial and generalized tonic-clonic seizures.

Precautions

Carbamazepine is contraindicated in the following conditions:

  • In patients who have a heart rhythm disorder (arrhythmias) or atrioventricular block. There have been reports of Carbamazepine-induced atrial tachycardia and atrioventricular block1,2, and therefore this medication should not be used in these patients.
  • In patients who have a low platelet count, low red blood cell count, or low white blood cell count, as well as in the patients who have bone marrow disorders. Numerous studies have shown that Carbamazepine can cause bone marrow suppression3,4 and consequently, thrombocytopenia, and leukopenia.5,6 If you notice symptoms of thrombocytopenia (e.g. prolonged bleeding from cuts, easy bruising, gum bleeding, nose bleeding or blood in the urine) or signs of leukopenia (flu-like symptoms, fatigue, frequent colds or stronger desire for warm drinks) immediately discontinue use and contact your doctor.
  • In patients with liver damage. There have been reports of liver damage induced by using this medicine.7
  • In patients who are taking medications for treating depression, the so-called MAO inhibitors (e.g. moclobemide, isocarboxazid, selegiline and phenelzine). Concomitant use increases the risk of serotonin syndrome, which is characterized by the occurrence of serious side effects.

If you notice the occurrence of suicidal thoughts, contact your doctor immediately. It is very important not to conceal this information from the family and doctors, so they can help you

It is preferred to check liver function (by using a simple blood tests to determine the levels of liver enzymes such as AST and ALT) before starting the treatment and then regularly during the course of treatment. If the levels of liver enzymes (AST and ALT) are two to three times higher than recommended, replacing of Carbamazepine with other antiepileptic medication should be considered.

Cases of serious and fatal dermatologic adverse reactions, such as: toxic epidermal necrolysis and Stevens-Johnson syndrome during the Carbamazepine therapy have been reported.

Carbamazepine, pregnancy and breastfeeding

The US FDA and Australian TGA classify this drug in group D - drugs that are proved to be teratogenic when administered during pregnancy! In one study that included 1255 pregnant women who used this drug during pregnancy has been found that Carbamazepine increases the risk of following malformations/abnormalities:

  • Cleft palate
  • Neural tube defect
  • Cardiovascular abnormalities
  • Urinary tract abnormalities

For this reason, use of Carbamazepine during pregnancy is not recommended. However, sometimes doctors choose to prescribe this drug to pregnant women because epileptic seizures, if left untreated, may also represent a risk to the life of both, mother and baby.

Mothers taking this medication can breastfeed their babies but if excessive sleepiness/drowsiness or allergic reactions on the skin of infants occur, than breastfeeding should be discontinued immediately.

Dosage

Adults

The usual starting dose is 100-200 mg once or twice daily. Maintenance dose is 200-400 mg two or three times per day. The maximum daily dose is 2000 mg.

The recommended dosage for the treatment of trigeminal neuralgia is 200 mg three to four times a day.

The recommended starting dose in the treatment of diabetic neuropathy is 100 mg once or twice a day. This dose can be gradually increased up to 200 mg three to four times a day.

The tablet should be swallowed whole with a little liquid and independently of meals.

Children

In children aged 5-10 years, the recommended dose is 200 mg two or three times per day.

In children aged 10-15 years, the recommended dose is 600-1000 mg per day.

Children younger than 5 years should use Carbamazepine syrup.

For children less than 4 years old, a starting dose is 20 - 60 mg / kg of body weight per day.

In children who are younger than 1 year, the recommended dose is 100-200 mg per day.

Interactions

Since Carbamazepine is a strong inducer of CYP3A4 enzyme responsible for metabolism of thousands of medicines, Carbamazepine interacts with many drugs, such as:

  • Antibiotics (clarithromycin, telithromycin, erythromycin and azithromycin)
  • Antidepressants (MAO inhibitors, selective serotonin reuptake inhibitors, and tricyclic antidepressants)
  • Antifungal drugs (ketoconazole, voriconazole, itraconazole, fluconazole, and others)
  • Antihistamines used to treat allergic reactions (e.g. loratadine)
  • Antipsychotics (olanzapine, clozapine, aripiprazole, loxapine, and others)
  • Acetazolamide - a drug used in the treatment of glaucoma
  • Platelet aggregation inhibitors (e.g. clopidogrel and ticlopidine)
  • Grapefruit juice
  • St. John's Wort
  • Anti-asthmatic drugs (aminophylline and theophylline)
  • Drugs used to treat tuberculosis (e.g. rifampicin and isoniazid)

Tell your doctor about all the medicines you are taking.

Side effects

Carbamazepine may cause the following side effects:

  • Ataxia
  • Drowsiness
  • Lassitude
  • Double vision
  • Nausea
  • Vomiting
  • Skin allergic reactions
  • Leukopenia
  • Thrombocytopenia
  • Eosinophilia
  • Pancytopenia
  • Anemia
  • Agranulocytosis
  • Leukocytosis
  • Lymphadenopathy
  • Acute intermittent porphyria
  • Aseptic meningitis
  • Urinary retention
  • Hallucinations
  • Anorexia
  • Depression
  • Suicidal thoughts
  • Dysarthria
  • Conjunctivitis
  • Glaucoma
  • Dry mouth
  • Glossitis
  • Pancreatitis
  • Stomatitis
  • Cholestatic hepatitis
  • Systemic lupus erythematosus
  • Alopecia
  • Hirsutism
  • Impotence
  • Oligospermia
  • Asthenospermia

References

  1. NCBI link 1
  2. NCBI link 2
  3. NCBI link 3
  4. NCBI link 4
  5. NCBI link 5
  6. NCBI link 6
  7. NCBI link 7