Also available in 5 mg, 10 mg, 25 mg, 50 mg, 200 mg, 500 mg and bulk. Please contact Fisher for quotes. Guanosine 5'-diphosphate disodium salt (5'-GDP-Na2) is a nucleoside diphosphate, is a potential iron mobilizer, which prevents the hepcidin-ferroportin interaction and modulating the interleukin-6 (IL-6)/stat-3 pathway. Purity 98%