Provided is a novel use of dorzolamide or a salt thereof. This preservative contains dorzolamide or a salt thereof. A pharmaceutical composition containing this preservative either does not contain or contains a prescribed amount of a preservative other than dorzolamide and salts thereof, and is kept in a multi-dose vial. Furthermore, the present invention relates to a product comprising a pharmaceutical composition and a multi-dose vial, said pharmaceutical composition either not containing or containing a prescribed amount of a preservative other than dorzolamide and salts thereof. The present invention further relates to a method for improving the preservative effect by further including dorzolamide or a salt thereof in a pharmaceutical composition kept in a multi-dose vial.本發明提供一種多佐胺(dorzolamide)或其鹽之新用途。本發明之防腐劑含有多佐胺或其鹽。含有本發明之防腐劑之醫藥組成物不含或含有特定量之多佐胺及其鹽以外之防腐劑且裝進多劑量型容器。又，本發明亦關於一種產品，其具備不含或含有特定量之多佐胺及其鹽以外之防腐劑之醫藥組成物以及多劑量型容器。再者，本發明亦關於一種方法，其藉由使裝進多劑量型容器的醫藥組成物中進而含有多佐胺或其鹽來提高防腐效果。
