PROBLEM TO BE SOLVED : To provide a compound and a composition for treatment of glaucoma and/or for reducing ocular tension. SOLUTION : A compound selected from the group consisting of the followings a) to c) : a) 2, 4-dimethylbenzoic acid (rac)-4-(3-amino-1-(isoquinoline-6-ylamino)-1-oxopropane-2-yl)benzylic dimesylate salt, b) 2, 4-dimethylbenzoic acid (R)-4-(3-amino-1-(isoquinoline-6-ylamino)-1-oxopropane-2-yl)benzylic dimesylate salt, and, c) 2, 4-dimethylbenzoic acid (S)-4-(3-amino-1-(isoquinoline-6-ylamino)-1-oxopropane-2-yl)dimethylbenzoic acid. The composition may contain an isoquinoline compound and a prostaglandin or a prostaglandin analogue. SELECTED DRAWING : Figure 1 COPYRIGHT : (C)2019, JPO&INPIT