Research Into Sorption Process of Levothyroxine With Alkyl-Substituted Chitosan Schiff-Based Hydrogel

Abstract

In order to reduce the side effects of thyroid hormone substitute levothyroxine sodium pentahydrate, its sorption with a quaternized salt of a new alkyl derivative of chitosan was studied. The drug amount in the salt (gel) is in micrograms, and the gel-levothyroxine is in the form of a complex that can show biological activity. With that end in view, a sorption process of levothyroxine sodium from an aqueous solution to the inside and surface of the hydrogel was carried out under static conditions. The capacity of the hydrogel depending upon the pH medium, the ionic strength, the hydrogel dose, the concentration of the drug and the temperature was studied. It was shown that the effective sorption of levothyroxine by chitosan-based hydrogel was optimal at pH of 6-8.5, at 50 mg/L concentration of levothyroxine in the presence of 10-50 mg of hydrogel dose but the sorption degree begins to decrease after T=40 °C. The isotherm results of sorption processes have been found to be subordinate mainly to Langmuir and to some extent Freundlich equations. It revealed that gel degradation in the oxidizing medium is about 70% within 2 weeks, and in the elastase and PBS medium is about 17-20%.