Pharmaceuticals are tested to confirm that they meet the requirements of the stability test guidelines of the Ministry of Health, Labor and Welfare before approval for their introduction is granted. All companies perform various severe tests at the preliminary stage of drug development. For eye drops, a nonionic surfactant is added to form micelles that include a fat-soluble active ingredient. In nonionic surfactants, we observe a phase transition temperature called the could point. At temperatures above the point, the surfactant will cause the yee drop to become cloudy, potentially impairing its product value.
We used our ELSZ series zeta potential/particle iamter measurement system to measure average particle diameter and the scattering intensity of commercially available eye drops after raising temperatures.
