Therapeutic safety monitoring: What to look for and when to look for it

This review focuses on the safety problems associated with antiepileptic dr ugs (AEDs) as revealed by laboratory testing and clinical examination. Ther e are two classes of side effects: (a) common and mild and (b) rare and sev ere. Allergic reactions to AEDs are common and usually mild. However, on ra re occasions, they can progress to more severe cutaneous disorders, includi ng Stevens-Johnson syndrome and toxic epidermal necrolysis. Severe allergic reactions to AEDs range from immune responses with fever to multiorgan dys function. Allergic rashes may be genetically or immunologically determined. Laboratory abnormalities produced by AEDs are common and mild, and include hepatic enzyme elevation associated with phenytoin and mild elevation in a mmonia associated with valproate. Serious, although rare, idiosyncratic sid e effects, such as aplastic anemia, hepatotoxicity, and thrombocytopenia, h ave also occurred with AEDs. These reactions are largely confined to the "c lassic" AEDs. With the exception of felbamate, AEDs approved in the past de cade have not been plagued by severe idiosyncratic reactions. Subtle endocr ine abnormalities, including variations in thyroid function tests and bone metabolism, and the often subclinical effects on peripheral nerve conductio n produced by phenytoin and carbamazepine; are also examined.