Anticonvulsant drugs adverse effects

I with seizures and require anticonvulsant therapy. Phenytoin is the most frequently used agent, with a loading dose of 15 mg/kg followed by 300 mg by mouth daily (titrated to therapeutic levels between 10 and 20 mcg/mL). Diazepam 5 mg intravenously may be used for rapid control of persistent seizures. Prophylactic anticonvulsants have been used frequently, but a recent meta-analysis did not support their use.23 Thus, because adverse effects and drug interactions are common, the routine use of prophylactic anticonvulsants is not recommended. 

De Ponti, F. et al., Immunological adverse effects of anticonvulsants What is their clinical significance, Drug Safety, 8, 235, 1993. 

Changes in body weight associated with anticonvulsants have been reviewed (116), including the effects of the antiepileptic drugs that have been most commonly associated with this adverse effect (valproic acid, carbamazepine, vigabatrin, and gabapentin) (117). Unlike most anticonvulsants, topiramate, felbamate, and zonisamide can cause weight loss. 

Carbamazepine has been considered to be a reasonable alternative to lithium when the latter is less than optimally efficacious. It may be used to treat acute mania and also for prophylactic therapy. Adverse effects (discussed in Chapter 24 Antiseizure Drugs) are generally no greater and sometimes are less than those associated with lithium. Carbamazepine may be used alone or, in refractory patients, in combination with lithium or, rarely, valproate. The mode of action of carbamazepine is unclear, but it may reduce the sensitization of the brain to repeated episodes of mood swing. Such a mechanism might be similar to its anticonvulsant effect. 

Wong I, Tavernor S, Tavernor R. Psychiatric adverse effects of anticonvulsant drugs incidence and therapeutic implications. CNS Drugs 1997 8 492-509. 

Pharmacokinetics. Carbamazepine is extensively metabolised one of the main products, an epoxide (a chemically reactive form), has anticonvulsant activity similar to that of the parent drug but may also cause some of its adverse effects. The t) of carbamazepine falls from 35 h to 20 h over the first few weeks of therapy due to induction of hepatic enzymes that metabolise it as well as other drugs, including corticosteroids (adrenal and contraceptive), theophylline and warfarin. Cimetidine and valproate inhibit its metabolism. There are complex interactions with other antiepilepsy drugs, which constitute a reason for monodrug therapy. 

Choreoathetosis is a rare adverse effect of some anticonvulsants, but has especially been associated with phenytoin. In a retrospective survey, three of 39 adults and one of 38 children developed choreoathetosis acutely when lamotrigine was added to phenytoin or vice versa (78). The effect was reversible by withdrawing one of the drugs. It was calculated that the risk of choreoathetosis is increased more than 50-fold when these drugs are combined, possibly owing to a pharmacodynamic interaction. 

Paraldehyde is the cyclic trimer of acetaldehyde, a colorless or slightly yellow-colored liquid. It has been used as an anticonvulsant, but because of its adverse effects and because it is difficult to use it has been replaced by more modern agents. However, it is still sometimes used to treat status epilepticus that is resistant to first-line drugs (1). The usual adult rectal dose is 10-20 ml. 

A number of important characteristics exist that distinguish drug therapy in infants from adult medication protocols. For example, after intramuscular administration, drug absorption is partially dependent on blood flow in the muscle bed. Abnormal drug absorption following intramuscular injection can occur in premature infants, in whom muscle mass is small and blood flow to the musculature is poor. Examples of adverse effects attributed to altered drug absorption are the reactions of infants to cardiac glycosides and anticonvulsants. 

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