ABSTRACT
Objective: Sodium valproate granules (VPA granules) are extremely hygroscopic, deliquesce slowly in the air, and aggregate depending on temperature and humidity conditions. Although pharmacists are required to maintain drug storage conditions until the time of dispensing, they cannot keep track of the actual storage conditions maintained by the patients thereafter. Therefore, we investigated the actual temperature and humidity of the storage conditions maintained by the patients after delivery of the VPA granules.Methods: We conducted a prospective observational study at Kameda Medical Center on pediatric outpatients who were prescribed VPA granules from July 5, 2018 to February 20, 2019. A portable data logger capable of measuring temperature and humidity for 24 h was delivered at the time of dispensation. At the following visit, the data logger was collected, and data about temperature and humidity were obtained. We defined the suitable temperature as 1.0-30.0℃ and suitable humidity as 75.0% or less.Results: In this study, 13 patients were included. In total, 18 data loggers were distributed, and the return rate was 100.0%. The storage temperature was outside the suitable range in 0.8% of the total observation time whereas the humidity exceeded 75.0% in 1.7% of the total observation time.Conclusion: Storage of medications after dispensation was evaluated, and certain temperature and humidity deviations were observed. As storing a drug in an inappropriate environment changes the nature of the drug, affecting its efficacy and safety, it is necessary to educate patients on the proper methods to store oral medications.