[Evidence-based quality management of clinical formulations: determination of expiration date of powdered medicine prepared by grinding tablets].

Beraprost sodium (BPS) is often used for pediatric patients with pulmonary hypertension. The purpose of this study was to determine the expiration date of the powdered medicine prepared by grinding tablets. In the present study, the hygroscopicity and stability of the beraprost tablet (DORNER tablet), ground Dorner tablet and powder formulation (Dorner powder) consisting of the ground DORNER tablet and lactose (EFC lactose) were investigated after storage at various relative humidities (RHs) and light exposures. While the DORNER tablets and ground DORNER tablets were found to adsorb significant amounts of water vapor at an RHs of greater than 51.0%, Dorner powder scarcely adsorbed water. The stability of BPS in the Dorner powder decreased after storage under 3000 lux for 90 days. From these results, the expiration date and storage conditions of Dorner powder were determined to "90 days without exposure to light." We also investigated the stability of BPS in solutions of various pH values on the assumption that Dorner powder may be given to pediatric patients after dissolving in soft drinks. Because BPS degraded significantly below pH 2, pharmacists should alert patients not to take Dorner powder with acidic soft drinks.