Relative effectiveness coefficient: a quality characteristic of toothpastes containing active components

It has been proposed that the parameter of relative effectiveness coefficient (REC) be used for the qualitative assessment of toothpastes containing active ingredients. REC is the ratio between the concentration of the active component in water eluates obtained after three minutes and adequately prolonged (up to the reaching of equilibrium state) dispersion of the toothpaste in distilled water at a 1:4 ratio (condition simulating the use of toothpaste in the oral cavity). The change in REC after storage following its production, as well as testing the toothpaste stability at high and low temperatures, provides an evidence for deviations in its quality. REC was applied for the assessment of toothpastes containing 0.5% zinc citrate as an active ingredient.