The Physical Properties and Cost Evaluations of Brand-name Versus Generic Eyedrops for Glaucoma

Abstract

The aim of the study is to explore the differences of physical properties and cost evaluations between a brand-name product and 4 generic products of latanoprost/timolol combination eyedrops. A squeeze force which is needed to make one drop, a weight of one drop and the total number of drops were measured by a Digital forcegauge (ZTS-500N, IMADA Co., Ltd). A cost of one drop was calculated based on a drug price of each product. The maximum weight of one drop was 27.13 mg of the brand-name product, which was significantly heavier than those of all the generic products (p<0.01). The squeeze force of the brand-name product was 3.05 N, while those of generic products ranged from 2.75 N to 7.24 N. The minimum of the total number of drops was 104 of the brand-name product, which was significantly fewer than those of all the generic products (p<0.01). A cost of one drop of the brand-name product was 24.42 Japanese Yen (JPY), while that of generic products ranged from 10.17 to 10.71 JPY. Since the total number of drops exceeds 100 in all the products, it is assumed that a drug solution will remain after the expiration date. Therefore, it is suggested to reduce the total amount of the drug solution in each product. Though a product with a small squeeze force is easy to be applied, it has a concern of dripping. A further study is needed to investigate the relationship between dripping and feeling of use of these products.