Abstract: Introduction: MC710 is a mixture agent consisting of plasma-derived activated factor VII (FVIIa) and factor X (FX) at a weight ratio of 1:10 developed as a novel bypassing agent for the management of the bleeding of hemophilia patients with inhibitors. The pharmacokinetics, distribution, and excretion of 125I-labeled-FVIIa (125I-FVIIa) and -FX (125I-FX) were studied in male rats after a single intravenous administration of 125I-FVIIa or 125I-FX combined with MC710. Methods: 125I-FVIIa or 125I-FX was administered intravenously with MC710 to male rats in a single dosage (FVIIa 0.4mg and FX 4mg/kg body weight) and radioactivity and antigen levels in plasma were quantified for 24h. Urine and feces were sampled to study the excretion of radioactivity during 168h after dosing. Whole-body autoradiography was performed to evaluate the qualitative distribution of radioactivity 168h after dosing. Results and conclusions: The half-life (t1/2α and t1/2β) of radioactivity and FVIIa antigen were 0.704 and 6.27h, and 0.496 and 1.66h, respectively and the area under the plasma concentration–time curve (AUC0–∞) of radioactivity and FVIIa antigen were 17,932 and 8671ng·h/mL, respectively. The t1/2 of radioactivity and FX antigen were 4.06 and 3.05h, respectively, and the AUC0–∞ of radioactivity and FX antigen were 320,143 and 395,794ng·h/mL, respectively. About 80% of the administered dose of radioactivity was excreted in urine and feces by 168h after administration. Tissue distribution experiments showed that FVIIa- and FX-related 125I accumulated in bone and bone marrow, and disappeared slowly. [Copyright &y& Elsevier]