2019 Volume 38 Pages 9-13
Latanoprost is the most commonly used glaucoma drug in humans, and lowers intraocular pressure (IOP) by increasing the outflow of aqueous humor through the uveoscleral pathway. In this study, the usefulness of 0.005% latanoprost ophthalmic solution (VETLATAN®, Senju Pharmaceutical Co., Ltd., Osaka) was investigated by performing a pharmacological, pharmacokinetic, and toxicological study in dogs. IOP significantly decreased after a single topical administration of 0.005% latanoprost ophthalmic solution, although it tended to return to baseline 20 hours after administration. In contrast, twice administration of the drug, 12 hours apart, caused significant IOP reduction that persisted at a low level for 24 hours after administration. Aqueous humor concentration of latanoprost free acid, an active form of latanoprost, was 3.3 nM 8 hours after a single topical administration of the drug. This concentration was lower than the half maximal effective concentration (EC50: 3.6 nM) of latanoprost free acid for stimulating the prostaglandin FP receptors, resulting in reduced efficacy of IOP reduction. Furthermore, after repeated topical administration, an extremely small amount of latanoprost free acid was detected in plasma, and no significant toxicity was observed. These results support veterinary clinical-usefulness in treating glaucoma with twice-daily topical administration of 0.005% latanoprost ophthalmic solution in dogs.
