The adsorption of simvastatin on chitosans in an in vitro pharmaceutical model

In clinical practice for the treatment of obesity, several natural macromolecular compounds are used, whose operation is based on supporting weight loss. During the use of dietary supplements containing chitosan, disease sometimes occurs and treatment for this often comprises different therapeutic agents and antibiotics. The aim of our study was to determine the binding capacity of simvastatin to chitosan, which is found in dietary supplements promoting weight loss, depending on variable physicochemical factors in the gastrointestinal tract model. The phenomenon of adsorption of simvastatin was investigated by a static and dynamic pharmaceutical model (according to the Modified method of Polish Pharmacopoeia IX) simulating the conditions in vitro. The amount of bound drug is used to calculate the average percentage of the adsorbed dose. The obtained results showed that simvastatin is adsorbed by chitosan in the used pH ranges, and the binding capacity is dependent on the environmental pH, viscosity, the concentration of the drug, the type of chitosan and additional substances present in the gastrointestinal tract. The average adsorption of simvastatin in the system of chitosan-nutrients, depending on the pH of the medium, was in the range of 27 to 95%. The highest amount of adsorption was noted above pH 7 (chitosan precipitated polymer forming the emulsion-gel system), when the bioavailability of dietary supplement using chitosan was almost zero.