In the present study, 0.5% povidone-iodine solution was prepared aseptically using various commercial products of 10% povidone-iodine solution, and the stability of 0.5% povidone-iodine solution after storage under various conditions was evaluated. Furthermore, a comparison between various commercial products was also performed. As a result, the stability of available iodine in 0.5% povidone-iodine solution was found to be affected by light, temperature and the sealability of the container. Of the storage methods investigated in the present study, the method of keeping the highest available iodine concentration was to store the povidone-iodine solution in a closed container under a light-shielded state at 4°C. The term of validity was 3 or 4 weeks in Hisiiode disinfectant solution or other products (Isodine® solution, Popiyodon solution, Negmin® solution, Popyral disinfectant solution and Iodine M disinfectant solution), respectively in storage in a closed container under a light-unshielded state at room temperature, which was the usual method of a disinfectant, from the results of a stability test of available iodine in 0.5% povidone-iodine solution. It was confirmed that bactericidal activity was maintained until at least 4 weeks after preparation in every commercial product from the results of a bactericidal activity test on the solution in the usual storage method (Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Aspergillus niger, Candida albicans). Of the 0.5% povidone-iodine solution investigated in the present study, Popiyodon solution and Negmin® solution kept the available iodine comparatively stable under each storage condition.
