Carbamazepine has effects on serotonin systems but the relevance to its antiseizure effects is uncertain. There is evidence that it is a serotonin releasing agent and possibly even a serotonin reuptake inhibitor. It has been suggested that carbamazepine can also block voltage-gated calcium channels, which will reduce neurotransmitter release. Pharmacokinetics
Carbamazepine is relatively slowly but practically completely absorbed after administration by mouth. Highest concentrations in the blood plasma are reached after 4 to 24 hours depending on the dosage form. Slow release tablets result in about 15% lower absorption and 25% lower peak plasma concentrations than ordinary tablets, as well as in less fluctuation of the concentration, but not in significantly lower minimum concentrations.20 to 30% of the substance are circulating in form of carbamazepine itself, the rest are metabolites. 70 to 80% are bound to plasma proteins. Concentrations in the breast milk are 25 to 60% of those in the blood plasma.Carbamazepine itself is not pharmacologically active. It is activated, mainly by CYP3A4, to carbamazepine-10,11-epoxide, which is solely responsible for the drugs anticonvulsant effects. The epoxide is then inactivated by microsomal epoxide hydrolase (mEH) to carbamazepine-trans-10,11-diol and further to its glucuronides. Other metabolites include various hydroxyl derivatives and carbamazepine-N-glucuronide.The plasma half-life is about 35 to 40 hours when carbamazepine is given as single dose, but it is a strong inducer of liver enzymes, and the plasma half-life shortens to about 12 to 17 hours when it is given repeatedly.
Carbamazepine (CBZ), sold under the trade name Tegretol among others, is an anticonvulsant medication used primarily in the treatment of epilepsy and neuropathic pain. It is used as an adjunctive treatment in schizophrenia along with other medications and as a second-line agent in bipolar disorder. Carbamazepine appears to work as well as phenytoin and valproate for focal and generalized seizures. It is not effective for absence or myoclonic seizures.Carbamazepine was discovered in 1953 by Swiss chemist Walter Schindler. It was first marketed in 1962. It is available as a generic medication. It is on the World Health Organizations List of Essential Medicines. In 2018, it was the 204th most commonly prescribed medication in the United States, with more than 2 million prescriptions. The newer but structurally related drugs, Oxcarbazepine and eslicarbazepine acetate, both show similar interactions, adverse events, and mechanism of action profiles. Medical uses
Carbamazepine is typically used for the treatment of seizure disorders and neuropathic pain. It is used off-label as a second-line treatment for bipolar disorder and in combination with an antipsychotic in some cases of schizophrenia when treatment with a conventional antipsychotic alone has failed. However, evidence does not support this usage. It is not effective for absence seizures or myoclonic seizures.