Impact of topiramate on serum bicarbonate concentrations in adults.
BACKGROUND
Topiramate is an antiepileptic medication with multiple pharmacologic effects, including inhibition of carbonic anhydrase activity. It is associated with metabolic acidosis in both children and adults.


OBJECTIVE
To evaluate the incidence and magnitude of the effect of topiramate on serum bicarbonate concentrations in an adult population.


METHODS
This was a retrospective cohort study. Data were evaluated to assess the relationship between serum bicarbonate concentrations before and during topiramate therapy.


RESULTS
Fifty-four patients (40 females) with a mean age of 47.6 years (range 19-89) were included in the study. Mean +/- SD serum bicarbonate concentrations before and during topiramate therapy were 26.8 +/- 2.9 mEq/L (range 21-36) and 21.7 +/- 3.6 mEq/L (range 13-29), respectively, with a mean difference of 5.1 (95% CI 3.7 to 6.5; p < 0.001). Twenty-six patients (48%) had low serum bicarbonate concentrations while on topiramate, with a mean concentration of 18.8 mEq/L (range 13-21).


CONCLUSIONS
Topiramate was associated with metabolic acidosis in 48% of the patients studied, which did not result in clinically significant problems.
Garris
Shauna S
SS
Department of Pharmacy, Medical University of South Carolina, Charleston, SC, USA.
Oles
Karen S
KS
D000138:Acidosis / Q000139:chemically induced*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000927:Anticonvulsants / Q000009:adverse effects* / Q000627:therapeutic use; D001639:Bicarbonates / Q000097:blood*; D015331:Cohort Studies; D004827:Epilepsy / Q000188:drug therapy; D005260:Female; D005632:Fructose / Q000009:adverse effects* / Q000031:analogs & derivatives* / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D000077236:Topiramate
D000927:Anticonvulsants; D001639:Bicarbonates; D000077236:Topiramate; D005632:Fructose