Comparative Evaluation of the Pharmaceutical Properties and Economics of Ethical and Rx-OTC-switch Anti-allergy Ophthalmic Solutions

Abstract

To provide appropriate information concerning ethical or Rx-OTC-switch drugs containing the same ingredients by pharmacists, it is necessary to understand the properties of both. In this study, pharmaceutical properties and economics were compared between ethical and Rx-OTC-switch anti-allergy ophthalmic solutions containing tranilast, pemirolast, or acitazanolast. Regarding 14 ethical and 3 Rx-OTC-switch products, the squeeze force, drop weight, pH, specific gravity, and total number of drops were measured. The usable period per bottle and daily cost were calculated from the total number of drops. The squeeze forces of the three drugs differed about 1.5-2 times among their products. Single-drop volumes calculated from the drop weights and specific gravities ranged from 30 to 46 μL for 0.5％ tranilast ophthalmic solution, larger for the original drugs than for the Rx-OTC-switch and generic ones. The pH values of the ophthalmic solutions differed among the drugs, but not among their products. The usable periods of each bottle of the three drugs were longer for the Rx-OTC-switch drugs. However, the daily drug costs of 0.1％ pemirolast ophthalmic solution were higher for the Rx-OTC-switch drug than for the original one, although those of 0.5％ tranilast ophthalmic solution were lower. The present study demonstrated that the squeeze forces and drop volumes differed between the Rx-OTC-switch and ethical drugs and that the usable periods of each bottle and daily costs differed among the drugs. It is important for pharmacists to obtain information on the pharmaceutical properties and economics for in order to select products for individual patients.

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“…The hardness and squeeze characteristics of each eye drop container are important not only in terms of ease of use, but also in terms of economy. Murakami et al reported that the shape of the eye drop container, the material of the main body, and the hardness of the container can influence the squeeze characteristics (15). Similarly, the squeeze force was reported to be affected by the material and hardness of the container, whereas the drop volume is affected by the surface tension of the eye drops and the opening diameter of the nozzle tip of the container (16).…”