Coagulation, of blood

The mass percentage composition of a compound that assists in the coagulation of blood is 76.71 % C, 7.02% H, and 16.27% N. Determine the empirical formula of the compound. 

Warfitrin and dicoumaroi prevent coagulation only in vivo and cannot prevent coagulation of blood in vitro (drawn from a patient into a test tube). 

Drugs that decrease the coagulability of blood, such as coumarins andhep-arin (A), are employed for the prophylaxis of thromboses. In addition, attempts are directed at inhibiting the aggregation of blood platelets, which are prominently involved in intra-arterial thrombogenesis (p. 148). For the therapy of thrombosis, drugs are used that dissolve the fibrin meshwork->fibrino-lytics (p. 146). 

The most important adverse effect is bleeding. With coumarins, this can be counteracted by giving vitamin Ki. Coagulability of blood returns to normal only after hours or days, when the liver has resumed synthesis and restored sufficient blood levels of clotting factors. In urgent cases, deficient factors must be replenished directly (e.g., by transfusion of whole blood or of prothrombin concentrate). 

Pharmacology Calcium is essential for the functional integrity of the nervous and muscular systems, for normal cardiac contractility and the coagulation of blood. It also functions as an enzyme cofactor and affects the secretory activity of endocrine and exocrine glands. 

Little intravascular coagulation of blood occurs in normal physiological conditions. Hemostasis involves the interplay of three procoagulant phases vascular, platelet, and coagulation) that promote blood clotting to prevent blood loss (Fig. 22.1). The fibrinolytic system prevents propagation of clotting beyond the site of vascular injury and is involved in clot dissolution, or lysis (Fig. 22.2). 

L B. Warfarin does not produce an anticoagulant effect in vitro. It inhibits coagulation of blood only in vivo, because the effect depends upon warfarin s effect in the liver on the production of clotting factors. Warfarin does not require conversion into an active drug. It inhibits the post-ribosomal carboxy-lation of glutamic acid residues in the vitamin K-dependent clotting factors. Therefore, heparin rather than warfarin is used when blood is collected from donors and stored. 

Vitamin K activity is associated with several quinones, including phylloquinone (vitamin Kj), menadione (vitamin K3), and a variety of menaquinones (vitamin K2). These quinones promote the synthesis of proteins that are involved in the coagulation of blood. These proteins include prothrombin, factor VII (proconvertin), factor IX (plasma thromboplastin), and factor X (Stuart factor). A detailed discussion of blood coagulation is found in Chapter 22. The vitamin K quinones are obtained from three major sources. Vitamin K is present in vari-... 

Coagulation of blood comprises the formation of fibrin. There are thirteen factors (synthesized in liver) which are involved in the coagulation of blood. 

These are the drugs used to reduce the coagulability of blood. They can be classified as in table 6.1.3. 

Calcium is the most abundant body constituent (approx. 2% of body weight). It controls excitability of nerves and muscles and regulates permeability of cell membranes. It act as intracellular messenger for hormones and autacoids and help in coagulation of blood. 

Blood coagulation Cortisol, similar to epinephrine, augments the coagulability of blood. 

Howell WH, The coagulation of blood. In The Harvey Lectures, Vol 12, Philadelphia Lippincott, 1918 272-323,... 

Effect of Chemical Structure and Surface Properties of Synthetic Polymers on the Coagulation of Blood. II. Protein and Platelet Interaction with Polymer Surfaces, Trans. Amer. Soc. Artif. Int. Organs (1968) 14, 250. 

Brown Recluse spider venom contains many diverse protein fractions including spreading factors and enzymes such as hyaluronidase, collagenase, protease, phospholipase, and others. These venom components cause coagulation of blood and, ultimately, the occlusion of small blood vessels at the bite site. This leads to local skin and tissue necrosis due to ischemia. Hemolysis of red blood cells may also occur. The normal inflammatory processes that follow, such as edema and hemorrhage, contribute to the tissue damage caused by the venom. 

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