The chronic management of seizures is determined after etiology has been ascertained and a decision regarding the need for long-term therapy has been made. Selection of antiepileptic drugs (AEDs) can be complex. It requires careful evaluation of the patient’s general medical condition and consideration of potential adverse effects of individual drugs. Several factors influence the choice of AED, including the type of transplant.
Allograft survival in patients treated with AEDs is an important issue. Renal allograft survival is decreased in patients treated with phenytoin or phenobarbital and steroids.59,60 Hence, discontinuing AEDs has been actively advocated.60
The half-lives of prednisolone61 and probably cyclosporine are decreased when phenobarbital, phenytoin, and carbamazepine are used. When these AEDs are used, the dosages of immunosuppressive drugs should be increased to ensure therapeutic immunosuppressant drug levels. To avoid this problem, valproic acid is a reasonable choice for patients other than liver transplantation patients and bone marrow transplantation (BMT) patients during engraftment. For liver transplant patients or those in hepatic failure, gabapentin or levetiracetam may be more appropriate.
During the 2- to 6-week period of BMT engraftment, both phenytoin and valproic acid should be avoided. Carbamazepine is relatively contraindicated in BMT patients, both during and after engraftment, because its major serious side effect is hematologic toxicity. Although oxcarbazepine is chemically related to carbamazepine, it has much less potential for hematologic toxicity. Reasonable choices for use during BMT engraftment include phenobarbital, gabapentin, and levetiracetam.
Many of the newer AEDs—gabapentin, lamotrigine, topiramate, zonisamide, levetiracetam, and oxcarbazepine—have negligible hepatic CYP450 enzyme-inducing activity and fewer systemic or neurologic side effects than older AEDs. Lamotrigine and oxcarbazepine are approved for monotherapy in adults and children with partial seizures. The others are indicated as adjunctive therapy.