Disclosed herein are methods of treating a mammal in need of a reduction in intraocular pressure by administering an intraocular formulation including a therapeutically effective amount of norketotifen for the reduction of intraocular pressure to the eye of the mammal in need thereof, wherein the intraocular formulation includes about 0.02 wt % to about 1.0 wt % norketotifen or a salt or an isomer thereof, calculated as the norketotifen free base. In certain aspects, the intraocular formulation is free from any added preservative and the intraocular formulation is self-preserving. Also included herein is a method of treating a human in need of a reduction in intraocular pressure by administering an intranasal formulation that includes a therapeutically effective amount of norketotifen for the reduction of intraocular pressure to the eye of the human in need thereof. Also, the beneficial effects of known drugs for high IOP are improved by co-administration with norketotifen.