Abstracts

Rationale: Ketogenic diet is a well established effective anti-epileptic method, used for patients with pharmacologically intractable epilepsy. One of its potential side effects is metabolic acidosis. Zonisamide and Topiramate are carbonic anhydrase inhibitors. Hence, they can also cause metabolic acidosis. This is to study the risk of developing severe acidosis in children on the ketogenic diet for intractable seizures, taking Topiramate (TPM) and/or Zonisamide (ZNS) versus those taking other anti-epileptic drugs (AEDs). Methods: This is a retrospective study over a four year period in a tertiary child neurology center. 72 patients (38 females and 34 males) on the ketogenic diet were studied. Age at initiation of diet is (0.16- 17.9 years, mean age 5.56). Data on acidosis was collected from 56 patients. The results were divided into two groups. Group A: 26 patients receiving a carbonic anhydrase inhibiting AED, 19 of whom are taking TPM, 7 taking ZNS. Group B: with 30 patients on other AEDs. The Bicarbonate (HCO3-) levels of the two groups were analyzed at baseline, induction, three months and six months visits. Results: In group A, HCO3- mean level is 18.83 (95% CI 17.92-19.74), whereas in group B, HCO3- mean level is 21.03 (95% CI 20.14-21.92). The difference between the two groups was statistically significant at baseline (p=0.001). However, there was no significant change in the HCO3- mean difference between the two groups over six months period (p=0.934). Conclusions: Patients taking a carbonic anhydrase inhibiting AEDs, have a lower HCO3 at baseline. However adding a ketogenic diet, does not seem to increase that risk for acidosis, compared to other patients taking AEDs that do not inhibit carbonic anhydrase.