Enzyme Inducers/Inhibitors
Inducers - Phenytoin, Carbamazepine, Phenobarbital, Oxcarbazepine, Topiramate
Enzyme inhibitors - Valproic Acid
Protein bound - Phenytoin, Valproic Acid
Inhibitors and Inducers cause bone loss - periodic DEXA scans, Oscal with Vitamin D TID (per Dr. Marcuse)
AED choice in Women
Enzyme inducers (EI), TPM, and OXC decrease OCP efficacy – discuss other methods of contraception
No AED is absolutely safe in pregnancy, though VPA has highest incidence of malformations. LTG and LEV are considered the safest options in pregnant women.
Women of child bearing age on AEDs should be taking folate (2mg)
Comorbidities and AED choice
Migraines - Valproic Acid and Topiramate
Mood stabilization - Lamotrigine, Valproic Acid, Oxcarbazepine
Avoid VPA in patients with hepatic failure, may raise ammonia levels
Valproic Acid, Phenytoin, Phenobarbital, Carbamazepine can cause trasaminitis
Renal stones is relative contraindication for Topiramate and Zonergan
With carbamazepine and oxcarbazepine consider pts risk factors for hyponatremia (old age, renal failure, concurrent use of other meds causing hyponatremia)
Avoid enzyme inducers in patients on HAART, s/p organ transplant, or on anti-neoplastic agents
Weight Gain & Weight Loss
Carbamazepine and Gabapentin is associated with 5-10 lb weight gain
Valproic Acid and Pregabalin is associated with 10-50lb weight gain in ⅓ of patients
Felbamate, Topiramate, Zonisamide cause weight loss
Monitoring Levels and Routine Blood Tests
Valproic Acid, Carbamazepine, Phenytoin, Phenobarbital check routine bloods and AED levels frequently for first 6-12 months, then yearly if stable
AED levels in other medications generally checked with initiation, seizure recurrence, or if there is some event that may alter levels
Keep in mind which AEDs can be given IV – Phenytoin, Valproic Acid, Lacosamide, Levetiracetam, Phenobarbital
(French, NEJM 2008)