Kinetic analysis by means of low-angle laser light scattering has been used for the investigation into active pharmaceutical ingredients solubility depending on the content of heavy isotope of hydrogen1 2H (D) in water. Rate constants of active pharmaceutical ingredient solubility differ approximately by ~1.5 times for the two types of water with different deuterium/protium ratios, natural deionized high-ohmic water (D/H= 140 ppm) and deuterium-depleted water (D/H= 4 ppm). Results are to be utilized in order to control the quality of pharmaceutical substances with the purpose of dissolution quantitative evaluation, as well as with the aim of tackling the issue of new active pharmaceutical ingredients' low solubility while developing drugs. � 2018 OMICS International. All rights reserved.