Mechanisms of antiepileptic drug resistance

Purpose of review The present review considers new developments in the study and our understanding of resistance to treatment with antiepileptic drugs in epilepsy. Recent findings Studies suggest that mechanisms of resistance to drug treatment that operate in other diseases may also be relevant in human and animal drug-resistant epilepsy. Immunohistochemical and molecular genetic data show that there is overexpression of a number of genes and proteins that mediate nonspecific resistance to drug treatment. In particular, there is upregulation of P-glycoprotein and multidrug resistance-associated proteins 1 and 2. These proteins appear to be expressed in cerebral parenchymal cell populations that do not normally do so. Work in animal models suggests that these proteins are able to reduce the local concentration of antiepileptic drugs. Although these proteins are therefore good candidates for mediators of drug resistance, there is still limited proof that they are functionally important in human drug-resistant epilepsy. Summary Careful attention needs to be given to the identification and confirmation of the practical importance of mechanisms postulated to underlie drug resistance in human epilepsy. If certain mechanisms are shown to be involved, then new therapeutic options for drug-resistant human epilepsy may be forthcoming.