In vitro evaluation of preabsorptive events of dispersed supramolecular aggregates by dynamic light scattering : Oral multivitamins as a model case

In order to develop an approach to evaluate the preabsorptive behavior of supramolecular aggregate carriers, three commercial oral formulations of a mixture of lipophilic and hydrophilic vitamins dispersed in water-glycerin-polysorbate-80 (PS-80) vehicle were subjected to dynamic light scattering and electrokinetic determinations. They exhibited diffusion coefficients ranging from 4.46 .10^-9 to 3.22 .10^-8 cm²/s. To mimic in vivo environment the formulations were progressively diluted with water and simulated gastric and intestinal fluids until a ratio 1:10. Hydrodynamic diameters (d_H) at 37 °C and electrokinetic potentials of each formulation remained almost unchanged in the three assayed conditions. However, the average d_H were 1.00, 1.36 and 1.63 times higher than a reference dispersion of PS-80 revealing significant differences among formulations. Concentration of PS-80 in diluted samples is about 10³ times above its critical micellar concentration. Therefore, loaded core/shell micelles appears to be robust drug carriers that will interact with the gastrointestinal membranes upon administration. The observed differences in size and/or shape would be related to the biopharmaceutical performance of multisource products. Besides, the developed approach could be used in developing and control stages of such pharmaceutical systems. Colegio de Farmacéuticos de la Provincia de Buenos Aires