Known brand names include Tegretol and Epitol.
An antiepileptic (anticonvulsant) taken by mouth as tablets, extended-release tablets, or a liquid suspension. It treats several seizure types and the facial nerve pain of trigeminal neuralgia. Its boxed warning covers severe skin reactions, linked to the inherited HLA-B*1502 gene variant, and rare but serious drops in blood cells.
Exactly how carbamazepine works is not known, but it reduces the abnormal electrical activity in the brain that drives seizures. In animal studies, it dampens signals passed along chains of nerve cells and blocks the extra strengthening of signals that follows a burst of rapid firing. For trigeminal neuralgia, it changes the way the body senses pain, and in animals it greatly reduces pain from stimulating a nerve in the face. The liver, mainly through an enzyme called CYP3A4, turns it into carbamazepine epoxide, a breakdown product that also blocks seizures in animals.
With regular tablets, blood levels peak about 4 to 5 hours after a dose, compared with about 1.5 hours for the liquid and 3 to 12 hours for the long-acting tablets. It speeds up its own breakdown over the first 3 to 5 weeks, so the time it stays in the body shortens from 25 to 65 hours at first to about 12 to 17 hours. It also speeds the breakdown of many other medicines, such as hormonal birth control, which can then work less well. Its mild anticholinergic action, which blocks some nerve signals that use acetylcholine, can raise pressure inside the eye, and dizziness, drowsiness, and unsteadiness are most common early on.
Sources: [1]
Carbamazepine is a seizure medicine. It treats partial seizures that begin in one part of the brain, such as the temporal lobe, as well as tonic-clonic seizures, which cause stiffening and jerking of the whole body, and mixed patterns that include these types. It also eases the pain of trigeminal neuralgia, a condition that causes sudden, severe stabbing pain along a nerve in the face. It helps control seizures and this nerve pain, but it does not cure the condition behind them.
Adults and children take it by mouth as regular tablets, long-acting tablets, or a liquid, usually with meals. It can be used alone or added to other seizure medicines. It does not appear to control absence seizures, the brief staring spells once called petit mal, and in some people whose seizures include atypical absence spells it has made convulsions more frequent. It is not a simple painkiller and is not meant for minor aches or pains.
Dizziness, drowsiness, unsteadiness, nausea, and vomiting are the most common effects, especially early in treatment. The boxed warning covers severe, sometimes fatal skin reactions (Stevens-Johnson syndrome and toxic epidermal necrolysis), which are far more likely in people who carry the HLA-B*1502 gene variant, and a rare but serious drop in blood cells (aplastic anemia and agranulocytosis). The label also warns about allergic reactions that involve the whole body or swell the face and throat, low blood sodium, liver injury, heart rhythm problems, suicidal thoughts, and worse seizures if it is stopped suddenly.
A clinician may order these while someone is taking it.
This is the boxed warning, the warning the FDA label prints first.
Serious, sometimes fatal skin reactions (SJS and TEN), about 10 times more common in some Asian countries and strongly linked to HLA-B*1502. Screen patients with at-risk ancestry before starting, and do not treat allele-positive patients unless the benefit clearly outweighs the risk. Aplastic anemia and agranulocytosis occur 5 to 8 times more often than in the general population; get complete baseline blood counts, monitor closely if counts fall, and consider stopping for significant bone marrow depression.
Sources: [1]