Source of information: Drugbank (External Link). Last updated on: 3rd July 18
*Trade Name used in the content below may not be the same as the HSA-registered product.
Active Ingredient / Synonyms
5-Carbamoyl-5H-dibenz(b,f)azepine | 5-Carbamoyl-5H-dibenz[b,F]azepine | 5-Carbamoyl-5H-dibenzo(b,F)azepine | 5-Carbamyl-5H-dibenzo(b,F)azepine | 5H-Dibenz(b,F)azepine-5-carboxamide | Carbamazepen | Carbamazepin | Carbamazepina | Carbamazépine | Carbamazepinum | CBZ | Carbamazepine |
An anticonvulsant used to control grand mal and psychomotor or focal seizures. Its mode of action is not fully understood, but some of its actions resemble those of phenytoin; although there is little chemical resemblance between the two compounds, their three-dimensional structure is similar. [PubChem]
For the treatment of epilepsy and pain associated with true trigeminal neuralgia.
Mechanism of Action
Carbamazepine inhibits sustained repetitive firing by blocking use-dependent sodium channels. Pain relief is believed to be associated with blockade of synaptic transmission in the trigeminal nucleus and seizure control with reduction of post-tetanic potentiation of synaptic transmission in the spinal cord. Carbamazepine also possesses anticholinergic, central antidiuretic, antiarrhythmic, muscle relaxant, antidepressant (possibly through blockade of norepinephrine release), sedative, and neuromuscular-blocking properties.
Carbamazepine, an anticonvulsant structurally similar to tricyclic antidepressants, is used to treat partial seizures, tonic-clonic seizures, pain of neurologic origin such as trigeminal neuralgia, and psychiatric disorders including manic-depressive illness and aggression due to dementia. The response to carbamazepine is variable and may be due to its variable transport, especially across the blood-brain-barrier. The transporter that may confer drug resistance is RALBP1.
In clinical studies, carbamazepine suspension, conventional tablets, and extended-release tablets delivered equivalent amounts of drug to the systemic circulation. However, it has been observed that the suspension is somewhat faster absorbed. Furthermore, the extended-release tablet is slightly slower than the conventional tablet. The bioavailability of the extended-release tablet is 89%, compared to the suspension. Plasma levels of carbamazepine are variable. The time to peak concentration for the different formulations are as follows: Suspension = 1.5 hours; Conventional tablets = 4-5 hours; Extended-release tablets = 3-12 hours.
Hepatic. CYP3A4 is the primary isoform responsible for the formation of carbamazepine-10,11-epoxide. This metabolite is active and shown to be equipotent to carbamazepine as an anticonvulsant. Carbamazepine is more rapidly metabolized to the aforementioned metabolite in younger patients than in adults. It also undergoes glucuronidation via UGT2B7, however this finding has been disputed.
72% of the dose is in the urine while 28% is in the feces. Hydroxylated and conjugated metabolites are largely what was recovered in the urine. 3% of the dose is recovered as unchanged carbamazepine.
Initial half-life values range from 25-65 hours, decreasing to 12-17 hours on repeated doses.
Mild ingestions cause vomiting, drowsiness, ataxia, slurred speech, nystagmus, dystonic reactions, and hallucinations. Severe intoxications may produce coma, seizures, respiratory depression, and hypotension
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