Unoprostone isopropyl ester (Rescula) is the clinically approved, prodrug form of unoprostone, which is a free acid analog of PGF2α. Both latanoprost and Rescula have been approved for the treatment of ocular hypertension. Both analogs of PGF2α are believed to act by increasing the rate of aqueous humor outflow through the uveoscleral pathway. Both drugs are believed to act as prodrugs, with endogenous esterases within the eye releasing the free acid active form of the drug. The typical does of Rescula (one drop of 0.12% solution) is nearly 100 times that of latanoprost. Rescula has very little activity on isolated DP or TP receptors, less than 0.0005% the activity of PGE2 on EP3 receptors, and about 3% of the activity of PGF2α on FP receptors.