Purpose: Sodium valproate, which is commonly repacked to assist with adherence to ensure seizure control, is hygroscopic and therefore sensitive to moisture. The aim of this study was thus to determine the stability implications of removing the enteric coated tablets from their original packaging and repackaging into a Dose Administration Aid (DAA) with storage under various environmental conditions.

Methods: Physicochemical stability of enteric coated sodium valproate tablets repackaged into a DAA and stored at controlled room temperature, accelerated and refrigerated conditions was evaluated for 28 days. A validated high performance liquid chromatography method was used for the quantitation of the drug content.

Results: Although the chemical stability (sodium valproate between 95 and 105% of labelled content) was maintained for 28 days for all storage conditions, for those tablets stored under accelerated conditions the integrity of the enteric coat was compromised after only 8 days.

Conclusions: Repackaging of enteric coated sodium valproate should be undertaken with caution and be informed by storage climate. This is particularly relevant for those patients living in hot, humid environments where they should be advised to store their DAA in a refrigerator.