Morphology and release kinetics of technetium-99m(V) dimercaptosuccinic acid loaded, poly(lactic-co-glycolic)acid microspheric delivery system. An experimental approach that may be used for targeted radiation treatment.

The aim of our studies was to formulate a system that delivers the required radiation dose to the tumor site and minimize the harm to other organs or tissues. The poly (lactic-co-glycolic acid, 75:25; 50:50) microspheric radiation delivery system was fabricated using double emulsion solvent evaporation technique for the encapsulation of technetium-99m(V)dimercaptosuccinic acid ((99m)Tc(V)DMSA). Microspheres of different sizes (0.2-20.0 mum) were prepared. The initial burst in microspheres with 10% and 1% poly vinyl alcohol (PVA) in the presence of poly ethylene glucol (PEG) was as 30% and 16% respectively, however the initial burst in microspheres without the PEG was 9% and 1.2% respectively. The results indicated that smaller microspheres had higher encapsulation (68%) of (99m)Tc(V)DMSA than larger microspheres (15%). The stirring rate changed the surface of the microspheres from smooth spherical, to spherical, porous. The ratio of co-polymers (75:25/50:50) affected the release kinetics. In conclusion, our studies with varied surfactant concentrations, co-polymer concentrations and speed of solvent evaporation, on the morphology and release kinetics of (99m)Tc(V)DMSA from the microspheres, may be applied for the fabrication of targeted radiotherapeutic microspheres by substituting (99m)Tc(V)DMSA with rhenium-188 (V) DMSA ((188)Re(V)DMSA). (188)Re(V)DMSA is a therapeutic analogue of (99m)Tc(V)DMSA and both share similar radiopharmaceutical properties.