B-vitamin deficiency in patients treated with antiepileptic drugs

Epilepsy Behav. 2012 Jul;24(3):341-4. doi: 10.1016/j.yebeh.2012.04.132. Epub 2012 May 31.


Enzyme-inducing antiepileptic drugs (AEDs) produce many alterations in metabolism, including vitamin levels. Whether they produce clinically relevant deficiency of B vitamins has rarely been assessed. We obtained B-vitamin levels in patients who were being converted from an inducing AED (phenytoin or carbamazepine) to a non-inducing AED (levetiracetam, lamotrigine, or topiramate), with measurements both before and ≥ 6 weeks after the switch. A group of normal subjects underwent the same studies. Neither folate nor B12 deficiency was seen in any patient. Vitamin B6 deficiency was found in 16/33 patients (48%) taking inducers, compared to 1/11 controls (9%; p=0.031). After switch to non-inducers, only 7 patients (21%) were B6 deficient (p=0.027). The incidence of deficiency was similar regardless of which inducing or non-inducing AED was being taken. Our findings demonstrate that treatment with inducing AEDs commonly causes pyridoxine deficiency, often severe. This could conceivably contribute to the polyneuropathy sometimes attributed to older AEDs, as well as other chronic heath difficulties.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Anticonvulsants / adverse effects*
  • Anticonvulsants / therapeutic use
  • Carbamazepine / adverse effects*
  • Carbamazepine / therapeutic use
  • Epilepsy / drug therapy*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Phenytoin / adverse effects*
  • Phenytoin / therapeutic use
  • Vitamin B Deficiency / chemically induced*


  • Anticonvulsants
  • Carbamazepine
  • Phenytoin