Effect of Ensure Liquid^® and Maalox^® on the Gastrointestinal Absorption of Sodium Valproate Syrup in Normal Subjects

Abstract

Sodium Valproate (VPA-Na) syrup is used in the management of patients following brain surgery for conditions such as traumatic injury or arteriovenous malformation. In our hospital, 65% of post-neurosurgical patients administered VPA-Na syrup were also given enteral nutrition (EN) and/or antacids (AA). We therefore investigated possible drug interactions between VPANa syrup and EN or AA. In a random crossover study, 250 mL of Ensure Liquid^® (EN), 20mL of Maalox^® (AA) or 50 mL of Purified water were administered to nine normal subjects mixed with 12mL Depakene^® (VPA-Na) syrup. Following administration, the serum concentration of valproic acid was then repeatedly measured over the next 48 hours using the FPIA method. Data were analyzed by non-parametric analysis and by population pharmacokinetic analysis using the NONMEM system. The results showed that the coadministration of Ensure and Maalox delayed the rate, but not the extent of bioavailability of VPA-Na syrup.