Which statement is true about carbamazepine?
Used in trigeminal neuralgia
Carbamazepine is an enzyme inhibitor
Can cause megaloblastic anemia
It is the drug of choice for status epilepticus
Ans. is 'a' i.e. Used in trigeminal neuralgia Trigeminal neuralgias are characterized by attacks of high intensity electric shock like stabbing pain, set off by even trivial stimulation of certain trigger zones in the mouth or on the face.Carbamazepine is not an analgesic but has a specific action in these neuralgias. It acts by interrupting temporal summation of afferent impulses (by a selective action on high frequency nerve impulses)."Carbamazepine has become the drug of choice for Trigeminal neuralgias "Other antiepileptic's such as phenytoin and Baclofen are less efficacious alternatives.More on carbamazepineThe most important action of carbamazepine is blockade of voltage dependent sodium ion channels, reducing membrane excitability.It is considered the drug of choice for partial seizures PharmacokineticsCarbamazepine is an extensively metabolized drug. One of the notable property of carbamazepine is its ability to induce microsomal enzymes (P450)The t 1/2 of carbamazepine decreases from 36 hrs. seen initially, to as short as 8-12 hrs due to its enzyme inducing property fit induces( its own metabolism)Due to its enzyme inducing property, carbamazepine effects the metabolism of other drugs too. ToxicityThe most common dose related adverse effects of carbamazepine are diplopia and ataxia.It may also cause hyponatremia and water intoxication.One more important adverse effect is idiosyncratic blood dyscrasias which may cause aplastic anemia and agranulocytosis.
C.N.S