This invention provides a pharmaceutical preparation for DDS containing a pharmaceutical agent fixed by bonding to a monomolecular layer that is covalently bonded to a magnetic particle surface, (a) by reacting an alkoxysilane compound with the magnetic microparticle surface by dispersing a magnetic microparticle in a liquid mixture including an epoxy-containing alkoxysilane compound, a silanol condensation catalyst, and a non-aqueous organic solvent (b) by washing the microparticle surface with an organic solvent to remove remaining surplus alkoxysilane compound for producing an epoxy-containing monomolecular layer that is covalently bonded to the microparticle surface and (c) by fixing an imino-containing pharmaceutical agent such as a protein, amino acid, enzyme, antibody, antibiotic, antimicrobial, or contrast medium by reaction with the epoxy group.
