초록 ▼

Thermally reversible polyurethane hydrogels are formed by adding water to a gel forming hydrophilic polyurethane polymer produced by reacting under anhydrous conditions a non-aromatic organic diisocyanate with a glycol component in an NCO/OH mole weight ratio of from about 0.900/1 to about 0.980/1,

Thermally reversible polyurethane hydrogels are formed by adding water to a gel forming hydrophilic polyurethane polymer produced by reacting under anhydrous conditions a non-aromatic organic diisocyanate with a glycol component in an NCO/OH mole weight ratio of from about 0.900/1 to about 0.980/1, the glycol component having a number average molecular weight of from about 1000 to 3500 wherein the percentage by weight of the diisocyanate in the reaction mixture is from about 7% to about 20%. The hydrogels are solids at room temperature but liquify at higher temperatures such as body temperature and therefore are useful as carriers for the protection, delivery and sustained release of a variety of active agents including pharmaceuticals, cosmetics, living cells and organisms.

대표청구항 ▼

A method of delivering an active agent to a treatment zone comprising the steps of: (1) mixing the active agent with a thermally reversible hydrogel in its liquid state, the said hydrogel comprising water and a hydrophilic polyurethane polymer produced by reacting under anhydrous conditions, an alky

A method of delivering an active agent to a treatment zone comprising the steps of: (1) mixing the active agent with a thermally reversible hydrogel in its liquid state, the said hydrogel comprising water and a hydrophilic polyurethane polymer produced by reacting under anhydrous conditions, an alkylene diisocyanate, bicycloalkane diisocyanate in which the rings are connected via ring carbon atoms by a single bond, or dicycloalkylalkane diisocyanate in which the rings are connected via ring carbon atoms through an alkylene chain, with a glycol component comprising one or more polyoxyethylene glycols, optionally mixed with one or more lower molecular weight ethylene glycols, in a mole weight NCO/OH ratio of from about 0.900/1 to about 0.980/1, the total glycol component having a number average molecular weight of from about 1000 to 3500 and the percentage by weight of the diisocyanate in the anhydrous reaction mixture is from about 10% to about 15%, mixing the reaction product in an aqueous medium, heating the mixture with stirring until homogeneous, (2) lowering the temperature of the liquid hydrogel to convert it into the solid gel form with concomitant encapsulation therein of the active agent; (3) introducing the solid hydrogel containing the encapsulated active agent to the treatment zone; and (4) raising the temperature of the solid hydrogel to convert it to the liquid form, thereby freeing the active agent to exert its therapeutic effect at the treatment zone.