Effect of antiepileptic drug polytherapy on urinary pH in children and young adults

Objects  The relationship between antiepileptic drugs (AEDs) polytherapy and urinary pH was studied to demonstrate the effect and difference of AED polytherapy compared to monotherapy. Materials and methods  A total of 271 urine samples from patients receiving AED polytherapy aged from 7 months to 35 years were enrolled. Two AEDs were co-administered to 215 patients, three AEDs to 45 patients, four AEDs to ten patients, and five AEDs to one patient. Results  The distribution of urinary pH shifted to the alkaline range with increasing numbers of co-administered AEDs (p < 0.0001). The distribution of urinary pH shifted to the alkaline side with AED polytherapy that included valproate (p < 0.05) or acetazolamide (p < 0.03). The distribution of urinary pH did not change with or without zonisamide, carbamazepine, phenobarbital, phenytoin, or clonazepam. Conclusions  Urinary pH should be monitored in patients receiving AED polytherapy, particularly those receiving valproate, acetazolamide, or various AEDs in combination.