Therapeutic agent for glaucoma

A method for treating glaucoma which comprises administering an effective amount of a therapeutic agent for glaucoma comprising, as active ingredient, a compound of the following formula (I) or its salt:

• wherein R1 represents one or more groups selected from the group consisting of a hydrogen atom, lower alkyl groups, halogen atoms, a nitro group, a hydroxyl group, lower alkoxy groups, lower alkanoyloxy groups, an amino group, lower alkylamino groups and lower alkoxycarbonyl groups, R2 represents a hydrogen atom, a lower alkyl group or a cycloalkyl group having 3 to 6 carbon atoms, R3 represents one or more groups selected from the group consisting of a hydrogen atom, lower alkyl groups, a hydroxyl group, lower alkoxy groups, halogen atoms, a nitro group, lower alkylenedioxy groups, lower alkanoyl groups, lower alkanoyloxy groups, an amino group, lower alkylamino groups, lower alkanoylamino groups and lower alkoxycarbonyloxy groups, or a group of —(CH2)b—, R4 represents a hydrogen atom or a lower alkyl group, A and B may be the same or different from each other and each represent a lower alkylene group having 1 to 6 carbon atoms, and n represents 3 or 4, and pharmaceutically acceptable diluent and/or carrier to a patient suffering from glaucoma.