抄録
Liquid crystal has been embedded in nylon membrane by vacuum filtration method to control the penetration rate of salbutamol sulfate. Cholesteryl oleyl carbortate(COC) which has smectic-cholesteric phase transition temperature near 18°C was used as a model liquid crystal. The results indicate the penetration rate of salbutamol sulfate through the COC-embedded membrane was dependent upon the adsorbed amount of COC in nylon membrane. At initial stage, the penetration rate of drug reduced dramatically with the increase of the adsorbed amount of COC. The adsorbed amount of COG was within 0.5 × 10-4-3.0 × 10-4 g mole/cm2 in which salbutamol sulfate was hardly to penetrate ; when the adsorbed amount of COC was within 3.0 × 10-4-9.0 × 10-4 g mole/cm2, the drug penetraion started again. After larger than 9.0 × 10-4 g mole/cm2 adsorption, the drug penetration stopped once more. Scanning electron microscopic (SEM) observation and water contact angle of the COC-embedded membrane might be used to explain this penetration result. The unique thermoresponsive property of COC-embedded membranes was proven in the step wise temperature change between 10°C and 25°C and made it possible to be used as thermally on-off switching membrane for stimuli-response controlled drug delivery system. The results indicate that thermo-responsive efficacy of such membrane is also depended upon the adsorbed amount of COC and the stimuli-responsive controlled membranes can be obtained by choosing an appropriate COC concentration and manufacturing processes.
