Carbamazepine in elderly causes:

Carbamazepine Chemically related to imipramine, it was introduced in the 1960s for trigeminal neuralgia; is now a first line antiepileptic drug. Carbamazepine modifies maximal electroshock seizures as well as raises threshold to PTZ and electroshock convulsions. It also inhibits kindling. Though its action on Na+ channels (prolongation of inactivated state) is similar to phenytoin, the profile of action on neuronal systems in brain is different. Carbamazepine exes a lithium-like therapeutic effect in mania and bipolar mood disorder. It also has antidiuretic action, probably by enhancing ADH action on renal tubules. Adverse effects Carbamazepine produces dose-related neurotoxicity-sedation, dizziness, veigo, diplopia and ataxia. Vomiting, diarrhoea, worsening of seizures are also seen with higher doses. Acute intoxication causes coma, convulsions and cardiovascular collapse. Hypersensitivity reactions are rashes, photosensitivity, hepatitis, lupus like syndrome, rarely agranulocytosis and aplastic anaemia. Some degree of leucopenia due to hypersensitivity is more common. Water retention and hyponatremia can occur in the elderly because it enhances ADH action. Increased incidence of minor foetal malformations has been repoed. Its combination with valproate doubles teratogenic frequency. Ref: K D Tripathi 8th edition