院内製剤塩化アルミニウム液の保存安定性

～処方にホウ砂やエタノールを添加すべきか～

抄録

Aqueous and ethanolic solutions of 10-20％ aluminum (Ⅲ) chloride hexahydrate are external medicines known as hospital preparations to reduce sweat. For many years, according to some prescriptions, the aqueous solution has contained 0.4-0.8％ borax. Here, we investigated the need for ethanol or borax addition in the preparation of aluminum (Ⅲ) chloride hexahydrate solutions from the viewpoint of stability. An aqueous solution of 18.09 w/v％ AlCl₃・6H₂O was prepared according to the prescription of Nissan-Tamagawa Hospital, Tokyo, Japan. The solution immediately showed pH 1.9, and the pH slightly increased after the addition of 0.8 w/v％ borax. The aluminum (Ⅲ) chloride hexahydrate solution became more acidic when prepared as a rubbing alcohol solution than when prepared as an aqueous solution. The aqueous solutions that did not contain borax were stable, showing no significant fluctuation in pH nor bacterial growth for six months of storage at both 25℃ and 40℃. Based on these results, aluminum (Ⅲ) chloride hexahydrate solution can be kept for at least six months at room temperature without the addition of ethanol or borax.