<p><strong>Background.</strong> There is a continued search for effective and safe drugs with systemic hemostatic effects. Experimental data from previous studies show that low-dose fibrin monomer (FM) can reduce posttraumatic bleeding without causing activation of clotting in the circulating blood.</p><p><strong>Aim.</strong> To study the systemic hemostatic and hemostasiological effects of prophylactic intravenous administration of FM on the background of fibrinolysis activation by streptokinase.</p><p><strong>Methods.</strong> In a placebo-controlled study using male rabbits, fibrinolysis was activated by intravenous administration of streptokinase at a dose of 150,000 IU/kg. One hour before liver injury, FM was administered intravenously at a dose of 0.25 mg/kg. Tranexamic acid (TXA) was administered intravenously at a dose of 15 mg/kg 30 min before injury as a reference drug. After metered-dose injuring, blood loss was estimated as % of the circulating blood volume and by the rate of blood loss (mg/s). The study of blood platelet count, activated partial thromboplastin time (APTT), thrombin time (TT), fibrinogen concentration and the results of rotational blood thromboelastometry were taken into consideration.</p><p><strong>Results.</strong> Administration of FM and TXA before fibrinolysis activation by streptokinase reduced the blood loss volume by 11.0 and 15.4 times, respectively. FM and TXA both reduced the blood loss rate by 3.8 times compared to the placebo group that received the same fibrinolytic. The administration of streptokinase in all cases was accompanied by 23–30% a decrease in the fibrinogen concentration without affecting APTT and TT. The hemostatic effects of FM and TXA were observed in vivo while preserving the density properties of the blood clot (according to the parameters of α angle, MCF and A10 in thromboelastometry) despite the administration of streptokinase, whereas a significant decrease in these parameters was observed in the placebo group.</p><p><strong>Conclusion.</strong> The systemic hemostatic effects of FM at a dose of 0.25 mg/kg with fibrinolysis activation by streptokinase were close to the effects of TXA. Thus, FM administration can be considered a promising hemostatic therapy for the reduction of thrombolysis-associated bleeding.</p><p>Received 18 December 2019. Accepted 22 January 2020.</p><p><strong>Funding:</strong> The study was supported by a grant from the Russian Foundation for Basic Research (No. 18-415-220001), Altai State Medical University.</p><p><strong>Conflict of interest:</strong> Authors declare no conflict of interest.</p><p><strong>Author contributions</strong><br />Conception and study design: A.P. Momot, V.M. Vdovin, I.I. Shakhmatov</p><p>Data collection: V.M. Vdovin, D.A. Orekhov, V.O. Krasyukova, N.A. Lycheva, D.A. Momot, V.E. Chernus, V.V. Terjaev</p><p>Data analysis: A.P. Momot, V.M. Vdovin</p><p>Drafting the article: V.M. Vdovin, A.P. Momot</p><p>Critical revision of the article: A.P. Momot, В V.M. Vdovin</p><p>Statistical analysis: V.M. Vdovin</p><p>Final approval of the version to be published: V.M. Vdovin, A.P. Momot, D.A. Orekhov, V.O. Krasyukova, I.I. Shakhmatov, N.A. Lycheva, D.A. Momot, V.E. Chernus, V.V. Terjaev</p>
