Pharmaceutical Titanium Dioxide Composite Allowing Disappearance of Drug Efficacy By Light Irradiation

Abstract

Disclosed is a titanium dioxide composite material which can be dispersed in an aqueous solvent stably and can be administered to a living body in a simple manner and in which the pharmacological effect of a therapeutic compound carried on the composite material can be eliminated by irradiation with light. Also disclosed is a dispersion product of the composite material. The composite material comprises titanium dioxide which has a photocatalytic activity and a therapeutic compound attached to the titanium dioxide through a hydrophilic polymer. The composite material is stable in an aqueous solvent and can be administered to a living body in a simple manner. After the composite material is administered to a living body, a site on the living body where the pharmacological effect of the therapeutic compound is not needed to be developed can be irradiated with light to induce the light excitation of titanium dioxide at the site, thereby decomposing the therapeutic compound to reduce any adverse side effect of the therapeutic compound.

1 . A titanium dioxide composite comprising:
 a titanium dioxide particle;   a hydrophilic polymer bonded to the surface of the titanium dioxide particle; and   a pharmaceutical compound having a desired drug efficacy and bonded to the hydrophilic polymer,   the pharmaceutical compound being decomposed by photoexcitation of the titanium dioxide to allow the drug efficacy to disappear.   
     
     
         2 . The titanium dioxide composite according to  claim 1 , wherein the hydrophilic polymer is a hydrophilic polymer having a carboxyl group bonded to a hydroxyl group on the surface of the titanium oxide particle by an ester bond. 
     
     
         3 . The titanium dioxide composite according to  claim 1 , wherein the titanium dioxide particle has a particle diameter of 2 to 200 nm. 
     
     
         4 . The titanium dioxide composite according to  claim 1 , wherein the pharmaceutical compound is an anticancer drug. 
     
     
         5 . The titanium dioxide composite according to  claim 4 , wherein the anticancer drug is adriamycin or bleomycin. 
     
     
         6 . A dispersion comprising the titanium dioxide composite according to any one of  claims 1  to  5  dispersed in an aqueous solvent. 
     
     
         7 . The dispersion according to  claim 6 , wherein the aqueous solvent has a pH of 3 to 13. 
     
     
         8 . The dispersion according to  claim 6 , wherein the aqueous solvent is a pH buffered solution or a physiological saline. 
     
     
         9 . The dispersion according to  claim 6  used in a method of treating a lesion, the method comprising the steps of administering the dispersion to an animal, and subsequently irradiating with UV light a region other than the lesion at least surrounding the lesion, without irradiating the lesion, to photoexcite titanium dioxide in a titanium dioxide composite contained in the dispersion, so that a pharmaceutical compound is decomposed by photoexcitation of the titanium dioxide to allow the drug efficacy to disappear. 
     
     
         10 . The dispersion liquid of surface-modified titanium dioxide fine particles according to  claim 9 , wherein the pharmaceutical compound is an anticancer drug and the lesion is a cancer tissue. 
     
     
         11 . A method of treating a lesion, comprising the steps of administering the dispersion according to  claim 6  to an animal including human, and subsequently irradiating with UV light a region other than the lesion at least surrounding the lesion, without irradiating the lesion, to photoexcite titanium dioxide in a titanium dioxide composite contained in the dispersion, so that a pharmaceutical compound is decomposed by photoexcitation of the titanium dioxide to allow the drug efficacy to disappear. 
     
     
         12 . The method according to  claim 11 , wherein the pharmaceutical compound is an anticancer drug and the lesion is a cancer tissue. 
     
     
         13 - 14 . (canceled)