A thermoswitchable membrane for drug delivery

Abstract

A thermoresponsive membrane was prepared by depositing cholesteryl oleyl carbonate (COC) in a cellulose nitrate membrane. The effect of the concentration of COC in the solution used to make the membrane and the effects of preparation and storage temperatures on membrane properties were explored. The thermophysical properties of COC were measured by differential scanning calorimetry. Two endothermic peaks were detected at 18.3° and 35.7°C due to smectic-cholesteric and cholesteric-isotropic liquid transitions, respectively. Two exothermic peaks were observed at 35.1° and 15.8°C during the cooling process. The IR spectra also showed changes at these transition temperatures. Thermal switching of the penetrability of the membrane was demonstrated in vitro using passage of salbutamol sulfate from a solution into water through a membrane barrier. The permeability was clearly con-trolled by temperature, suggesting that a COC-embedded membrane may be adapted to the control of drug delivery. The switchable membrane can be used to deliver drugs in a pulsatile fashion when this is desirable.