The present invention addresses the problem of providing a novel pharmaceutical composition that contains dorzolamide or a salt thereof and brimonidine or a salt thereof and exhibits a sufficient preservative effect. A pharmaceutical composition according to the present invention that contains dorzolamide or a salt thereof and brimonidine or a salt thereof has a pH of 6.0 or more. A pharmaceutical composition according to the present invention preferably does not include a preservative or includes a prescribed amount thereof, wherein said prescribed amount is preferably such that the logarithmic value of the ratio (B/A) of the number (B) of bacteria at the time of inoculation to the number (A) of bacteria when the number of viable bacteria is measured after inoculating bacteria in a test sample that comprises the preservative and water and mixing homogeneously such that the concentration of Escherichia Coli ATCC 8739 in the bacterial suspension is within the range of 105-106 cfu/mL, and collecting 1 mL of the test sample using a micropipette after the test sample has been stored for seven days at 20-25 DEG C while shielded from light, is 2.0 or less.本發明之課題在於提供一種新穎之醫藥組成物，其係含有多佐胺(Dorzolamide)或其鹽及溴莫尼定(Brimonidine)或其鹽者，並且能夠充分地發揮防腐效果。本發明之含有多佐胺或其鹽及溴莫尼定或其鹽之醫藥組成物之pH值為6.0以上。本發明之醫藥組成物較佳為不含防腐劑或以特定量含有防腐劑，特定量較佳為如下情況之量，即於由該防腐劑及水所構成之試驗試樣中，以大腸桿菌(Escherichia Coli)ATCC 8739之菌液濃度成為105~106cfu/mL之範圍內之方式接種菌並均勻地混合，將試驗試樣於避光下於20~25℃進行保存，經過7天後，利用微量吸管採取1mL試驗試樣，對活菌數進行測定，接種時之菌數(B)相對於對活菌數進行測定時之菌數(A)之比(B/A)之常用對數值成為2.0以下。
