CONTROLLED RELEASE OF DRUG BY MEMBRANE OF STIMULISENSITIVE POLYMER GEL

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Recently, reserches for the materials which control the release of drug inside themselves depending on the surrounding conditions have been attracting much attention because of their importance in many ( medical, pharmacy, agriculture, engineering) fields. In this reserch, the methods of release control of drug and its device design were studied in order to realize controlled release systems and establish its control methods. We obtained the folowing results from the viewpoint of both the physicochemical controlling method (system 1) and electrochemical controlling method (system 2).System 1 :The dependency of surface property (hydrophilic-hydrophobic balance) of thermosensitive N-isopropylacrylamide copolymer gels on the temperature was studied. These gels was found to have the potential for device which control the adsorption and desorption of organic matter onto them only by the temperature swing. We examined the effects of physicochemical structure of gel, solution pH, the hydrophi … More lic-hydrophobic balance of adsorbent and the structure of solution on the surface property of gel, and established the method of design for the device which had better adsorption property and mechanical strength.The shrinking mechanizm of gel was studied using ionic gel. The relationship between the transfer of ions through gel and shrinkage (solvent release) was well defined. The factors which control the release of solvent in the gel and the controlling method were mentioned in detail.System 2 :The method of controlling the surface property of thermosensitive polymer gel by electrochemical method were developed by means of the doping of weak acid group in the gel. The surface property of electrochemically controlled gel and its mechanizm were elucidated.The property of charge controllable membrane was studied to realize the control release of drug by iontophoresis using polypyrrol as membrane. It was found by the measurement of transport of drug in the membrane using quarts micro balance method that the permeation of drug through membrane can be easily controlled by the swing of electric potential which applied to the membrane. Less