153Sm metallic-hydroxide macroaggregates: An improved preparation for radiation synovectomy

A new type of preparation employing¹⁵³Sm metallic-hydroxide macroaggregates (¹⁵³Sm-MHM) for radiation synovectomy was developed. The radiopharmaceutical was prepared by reacting the aqueous solution of¹⁵³SmCl₃ with sodium borohydride solution in 0.5N NaOH. Microscopic analysis showed that¹⁵³Sm-MHM mean particle size was 4 m (range 1–15 m) avoiding the formation of fine particles (<1 m) which were¹⁵³Sm-hydroxide macroaggregates preparations (¹⁵³Sm-HM). Also, suspension properties as sedimentation rate, were better for¹⁵³Sm-MHM than for¹⁵³Sm-hydroxyapatite and¹⁵³Sm-HM. Biological studies in normal rabbits demonstrated high retention into de Knee joint space even at 48 h after administration of¹⁵³Sm-MHM (>99%).