Lymphatic delivery of 99mTc-labeled dextran acetate particles including cyclosporine A

Biodistribution and lymphoscintigraphy of cyclosporine A (CyA) and technetium-99m (99mTc) were studied using 99mTc-labeled dextran acetate (DxA) including CyA. DxA particles were prepared from dextran with acetic anhydride, and CyA was loaded into them. Lymphatic delivery of 99mTc-labeled DxA particles containing CyA was evaluated after subcutaneous injection into the foot pad of rats and compared with those of 99mTc-labeled human serum albumin (HSA). The labeling efficiency of CyA-loaded 99mTc-DxA particles was about 95% at 30 min. The labeling efficiency maintained stably above 80% for 12 h. The percent injected dose (%ID) of CyA-loaded 99mTc-DxA was similar to that of 99mTc-HSA at the inguinal lymph node after 40 min. The CyA-loaded 99mTc-DxA could be as well distributed as 99mTc-HSA through the lymph node. The DxA particles could steadily distribute the CyA as well as the 99mTc radiolabeling through the lymph node.