Modeling of drug release from a novel cylinder-shaped temperature-responsive drug delivery system

Temperature-responsive hydrogels are one of the most widely studied types of intelligent hydrogels. They can undergo a reversible volume phase transition due to a change in thepolymer and swelling agent compatibility by changing the temperature of the swelling medium as an external stimulus[1]. Drug delivery systems on the basis of temperatureresponsive hydrogels could release drug in a smart manner by increasing or decreasing the temperature of release medium.Numerous kinds of temperature-responsive drug delivery systems have been prepared on the basis of different kinds of temperature-responsive hydrogels and examined for practical applications [2]. In spite of the excellent potential of temperature-responsive hydrogels in production of smart drug delivery systems, one major limitation restricts their applications. In general, most of temperature-responsivehydrogels are not only responsive to the temperature, but also other stimuli can affect their responses. [3,4]. In this study and in order to overcome the aforementioned limitation, a novel multi-layer cylinder-shaped drug delivery system responsive only to temperature as an external stimuluswas introduced and the response of the system mathematically modeled by analyzing the heat and mass transfer equations in cylindrical coordinates at pseudo-steady state