Forskolin, a potent adenylate cyclase activator, lowers rabbit intraocular pressure.

To our knowledge, this is the first report of a topically applied, specific adenylate cyclase activator that reduces intraocular pressure. Forskolin, a novel adenylate cyclase activator, is reported to increase cyclic adenosine monophosphate (AMP) in intact cells. Cyclic AMP levels are increased with various antiglaucoma agents. Intraocular pressure in rabbits was significantly reduced with two concentrations of forskolin, 0.1% and 0.05%. Ocular hypertension was noted with 0.05% and 0.2%. No change in IOP was noted with 0.01% forskolin. The IOP lowering with 0.1% and 0.05% forskolin lasted approximately six hours. Mild, transient conjunctival chemosis was noted in the doses that decreased IOP. The contralateral control eye showed decreases in IOP, but the differences between control and tested eyes were significant by the Student's paired t test.