Text Size :
A A A

Carbamazepine

Brands and Forms

  • Carbatrol
    • Extended-release capsule: 100mg, 200mg, 300mg
  • Epitol
    • Tablet: 200mg
  • Equetro
    • Extended-release capsule: 100mg, 200mg, 300mg
  • Tegretol
    • Tablet, chewable: 100mg
    • Tablet: 200mg
    • Oral suspension: 100mg/5ml
  • Tegretol XR
    • Extended-release tablet: 100mg, 200mg, 400mg

Uses of Carbamazepine

In psychiatry, Carbamazepine is used most commonly in the treatment of Bipolar Disorder for Manic and Mixed Episodes as well as Depressive Episodes. It can also be used in cases of treatment-resistant Schizophrenia.

In general medicine, Carbamazepine is used for treating seizure disorders (epilepsy) and pain caused by trigeminal neuralgia.

How Carbamazepine Works

Carbamazepine is an anticonvulsant and mood stabilizer. It blocks voltage-sensitive sodium channels and inhibits the release of glutamate in the central nervous system.

Cautions when Using Carbamazepine

Individuals with a history of bone marrow suppression should avoid using Carbamazepine.

Carbamazepine can cause serious malformations to a fetus during pregnancy, and it can also reduce the efficacy of oral contraceptives. Therefore, women who are using Carbamazepine should consider using other forms of contraception.

Carbamazepine should not be used during or within 14 days following the administration of an MAOI, because a hypertensive crisis may result.

Dosing of Carbamazepine

Carbamazepine is usually started at 200mg twice a day (or 100mg four times a day of the suspension). It can be increased by up to 200mg/day every week. The extended-release forms can be given twice a day, whereas the dose of the tablets should be divided 4 times a day. The maximum dose is usually 1200mg/day for adults and 1000mg/day for children, though some patient will require up to 1600mg/day. The maintenance dose is generally 800-1200mg/day.

The therapeutic range of Carbamazepine blood concentrations is between 4-12 µg/ml, and the dose can be adjusted in such a way as to target this therapeutic range.

When wanting to stop this medication, the dose should be decreased gradually over a period of a few weeks.

Onset of action

For Manic and Mixed Episodes, therapeutic effects are usually seen within 2 weeks of starting Carbamazepine. Maximum therapeutic effects usually require several weeks or even a few months to be realized. If there are no signficant effects after 2-4 weeks at the higher end of the therapeutic range (4-12 µg/ml blood concentration) then the medication may not work at all.

Kidney impairment

Carbamazepine is excreted by the kidneys, so the dose may need to be lowered. Monitor dose according to blood levels.

Liver impairment

Drug should be used with caution.

Side-effects of Carbamazepine

Below is a list of most of the reported side-effects of Carbamazepine. Most of these side-effects occur in only a minority of individuals, and many can resolve with time while the medication is continued.

Cardiovascular: aggravation of coronary artery disease; aggravation of hypertension; arrhythmias, including AV block; congesitve heart failure; fainting; hypotension; syncope; thrombophlebitis.

Central Nervous System: dizziness; somnolence (can be significant in amount); headache; unsteadiness; memory problems; weakness; speech disorder; extrapyramidal syndrome; insomnia; aseptic meningitis with myoclonus; cerebral artery insufficiency; confusion; disturbances in coordination; hyperacusis; involuntary movements; paralysis; paresthesias; peripheral neuritis; talkativeness.

Dermatologic: rash; itchiness; hair loss; photosensitivity; aggravation of disseminated systemic lupus erythematosus; altered skin pigmentation; excessive perspirationl; hirsutism; erythema multiforme and Stevens-Johnson syndrome.

Endocrine/Metabolic: weight gain; hypothyroidism; decreased plasma calcium; elevated cholesterol, HDL cholesterol, and triglycerides; hyponatremia; SIADH.

Eyes, Ears, Nose and Throat: lazy eye; double vision; ear pain; pharyngitis; rhinitis; blurred vision; conjunctivitis; dry pharynx; nystagmus; tinnitus.

Gastrointestinal: nausea; vomiting; diarrhea; dyspepsia; dry mouth; constipation; abdominal pain; loss of appetite; glossitis; pancreatitis; stomatitis; elevated liver enzymes; hepatitis; liver failure.

Genitourinary: urinary tract infection; acute urinary retention; albuminuria; azotemia; elevated BUN; glucosuria; impotence; oliguria with elevated blood pressure; renal failure; urinary frequency.

Hematologic: leukopenia; lymphadenopathy; acute intermittent porphyria; adenopathy; agranulocytosis; aplastic anemia; bone marrow suppression; eosinophilia; leukocytosis; pancytopenia; thrombocytopenia.

Musculoskeletal: muscle stiffness; muscle pains; neuroleptic malignant syndrome (rare).

Psychiatric: anxiety; depressed mood; depersonalization; suicidal thoughts; visual hallucinations; psychosis; mania.

Respiratory: bronchitis; sinusitis; dyspnea; pneumonia; pneumonitis; pulmonary hypersensitivity.

Common side-effects of Carbamazepine

Dizziness, somnolence, headache, unsteadiness, amnesia, weakness, nausea, vomiting, diarrhea, dyspepsia, dry mouth.

Rare but serious side-effects of note of Carbamazepine

  • Aplastic anemia and agranulocytosis
  • Serious and potentially fatal allergic rashes, including a Stevens Johnson syndrome, have been reported in 1 to 6 per 10,000 Carbamazepine users. Studies in patients of Chinese ancestry found a strong association between the risk of developing Stevens-Johnson syndrome and the inherited genetic allelic variant HLA-B*1502. Screen patients who are genetically at risk and, if positive for the allele, when possible, do not prescribe carbamazepine.
  • Liver failure
  • Cardiac arrhythmias and congestive heart failure
  • SIADH
  • Rare induction of psychosis and mania.

Carbamazepine overdose

Nausea, vomiting, involuntary movements, irregular heartbeat, urinary retention, trouble breathing, sedation, coma. Can be fatal.

Carbamazepine and pregnancy

Carbamazepine can cause serious congenital malformations to the fetus, including neural tube defects when used in the first trimester. Using Folate 1mg/day starting early in pregnancy can help reduce the risk of these neural tube defects. In some severe cases of epilepsy, Carbamazepine is used in pregnancy, but in Bipolar Disorder or Schizophrenia it would be recommended to use an alternative treatment.

Medical Monitoring for Carbamazepine

Before starting Carbamazepine, the following medical tests should be obtained:

  • Complete blood count, to monitor for signs of aplastic anemia and agranulocytosis. Benign, transient leukopenia can occur in up to 10%.
  • Electrolytes, to monitor sodium and calcium levels, especially.
  • Liver function tests
  • kidney function tests
  • thyroid function tests
  • Lipids and cholesterol
  • Electrocardiogram

Once the medication is started, complete blood count should be measured every 2-4 weeks for the first 2 months, and then every 3-6 months thereafter. All of the other tests should be performed one month after starting the medication, and then every 6-12 months.

Drug Interactions with Carbamazepine

  • Carbamazepine can reduce the levels of the following medications: Acetaminophen, Aripiprazole, benzodiazepines, Bupropion, Citalopram, Clozapine, corticosteroids, Cyclosporine, Dicumarol, Doxycyclin, Felbamate, Felodipine, Haloperidol, Itraconazole, Lamotrigine, Lapatinib, Levothyroxine, Methadone, Olanzapine, Oxcarbazine, Praziquantel, Quetiapine, Risperidone, Sertraline, Simvastatin, succinimides, Tiagabine, Topiramate, Tramadol, Valproic Acid, Ziprasidone, Zonisamide.
  • Carbamazepine can decrease effects of oral contraceptives and anticoagulants.
  • The following medications may increase Carbamazepine levels and lead to toxicity: Acetazolamide, azole antifungal agents, Cimetidine, Danazol, Diltiazem, Isoniazid, grapefruit juice, Lamotrigine, Loratadine, macrolide antibiotics (except Azithromycin), Niacinamide, Nicotinamide, Propoxyphene, Quinine, Quetiapine, SSRIs, Terfenadine, Verapamil
  • The following medications may reduce Carbamazepine levels and effectiveness: barbituates, Cisplatin, Doxorubicin, Phenytoin, Primodine, Methsuximide, rifamycins (eg, Rifampin).
  • Carbamazepine can increase the levels of Clomipramine.