13,14-dihydro PGE1 is a biologically active metabolite of PGE1 with comparable potency to the parent compound. It is an inhibitor of ADP-induced platelet aggregation in human PRP and washed platelets with IC50 values of 31 and 21 nM, respectively. 13,14-dihydro PGE1 is a slightly more potent inhibitor of ADP-induced human platelet aggregation than PGE1 which has an IC50 of 40 nM. Also, 13,14-dihydro PGE1 was shown to activate adenylate cyclase in NCB-20 hybrid cells with a Kact of 668 nM.