Preparation and evaluation of radiopaque hydrogel microspheres based on PHEMA/iothalamic acid and PHEMA/iopanoic acid as particulate emboli.
Highly porous poly(2-hydroxyethyl methacrylate) (PHEMA) microspheres prepared by suspension polymerization of 2-hydroxyethyl methacrylate (HEMA) in presence of polymeric diluents such as poly(methyl methacrylate) (PMMA) in toluene and poly(tetramethylene glycol) (PTMG) were made radiopaque by esterification of the reactive hydroxyl groups with iothalamic acid and iopanoic acid, two radiopaque substances clinically used. Of the various solvents and catalysts examined, tetrahydrofuran (THF) and N,N'-dimethyl paratoluidine (DMPT) were found to be best for obtaining a high degree of conversion. More than 30 wt% iodine could be bound to the microspheres which made them sufficiently radiopaque to be imaged radiographically. Microspheres retained their porosity, swelling ability, hydrophilicity, and surface morphology to a significant extent after iodination. Preliminary implantation studies of such microspheres subcutaneously in rats have shown no adverse tissue reactions over a 6-month period. It is suggested that these microspheres would prove to be useful as particulate emboli in endovascular embolization.
Division of Polymer Chemistry, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India.
A
A
Jayakrishnan
B C
BC
Thanoo
K
K
Rathinam
M
M
Mohanty
D000818:Animals; D003287:Contrast Media; D004621:Embolization, Therapeutic / Q000379:methods*; D005069:Evaluation Studies as Topic; D005782:Gels; D007480:Iopanoic Acid; D007483:Iothalamic Acid; D008422:Materials Testing; D008854:Microscopy, Electron; D008863:Microspheres; D011102:Polyhydroxyethyl Methacrylate; D051381:Rats; D011919:Rats, Inbred Strains; D013499:Surface Properties
D003287:Contrast Media; D005782:Gels; D007483:Iothalamic Acid; D011102:Polyhydroxyethyl Methacrylate; D007480:Iopanoic Acid