Impact of Topiramate on Serum Bicarbonate Concentrations in Adults

• Published in: The Annals of pharmacotherapy 2005-03, Vol.39 (3), p.424-426
• Main Authors: Garris, Shauna S, Oles, Karen S
• Format: Article
• Language: English
• Subjects: Acidosis - chemically induced; Adult; Aged; Aged, 80 and over; Anticonvulsants - adverse effects; Anticonvulsants - therapeutic use; Bicarbonates - blood; Biological and medical sciences; Cohort Studies; Drug toxicity and drugs side effects treatment; Epilepsy - drug therapy; Female; Fructose - adverse effects; Fructose - analogs & derivatives; Fructose - therapeutic use; Humans; Male; Medical sciences; Middle Aged; Miscellaneous (drug allergy, mutagens, teratogens...); Pharmacology. Drug treatments; Retrospective Studies
• ISSN: 1060-0280; 1542-6270
• DOI: 10.1345/aph.1E437

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.