Development of 166Ho Poly Lactic Acid Microspheres for Radiosynovectomy

Microsphere and particle technology with selective transport of radiation represents a new generation of therapeutics in radiosynovectomy. 166Ho-PLLA-MS (Poly L-lactic acid microspheres loaded with holmium-166 acetylacetonate) are novel microdevices for intra-cavital radiosynovectomy in this work. 166Ho- PLLA agent was developed and quality controls of the compound were described. 165HoAcAc-PLLA microparticles were prepared by dissolving holmium acetylacetonate and incorporating into PLLA spheres by the solvent evaporation technique. Microspheres were irradiated at TRR (tehran research reactor). The diameter and surface morphology were characterized by particle sizer and SEM (scanning electron microscopy) before and after irradiation. The complex stability, radiochemical purity and in vivo biodistribiotion were checked in the final solution up to 3 days. In this study, 166Ho-PLLA spherical particles with a smooth surface and diameter of 5-10 μm were obtained, which were stable in vitro and in vivo studies. Neutron irradiation did not damage the particles, and heightened activity stimulated radiosynovectomy. No significant leakage of dose from injection site and its distribution in organs was observed up to 3 days for 166Ho-PLLA. The ease with which the PLLA spheres could be made in the optimal size range for later irradiation and their ability to retain the 166Ho made them attractive agents for radionuclide synovectomy.