Embolism/thrombosis derivatives

Retardation of clotting is important in blood transfusions, to avoid thrombosis after surgery or from other causes, to prevent recurrent thrombosis in phlebitis and pulmonary embolism. and to lessen the propagation of clots in the coronary aitcries. This retardation may be accomplished by agents that inactivate thrombin (heparin) or substances that prevent the fotmation of prothrombin in the liver (the coumarin derivatives and the phenylindanedione derivatives). 

Dipyridamole is a pyrimidopyrimidine derivative with vasodilatory and antiplatelet properties (Fig. 31.17). Dipyridamole exerts its antiplatelet function by increasing cellular concentrations of cAMP via its inhibition of the degradating enzyme, cyclic nucleotide PDE3. It also blocks adenosine uptake, which acts at A2 adenosine receptors to stimulate platelet adenyl cyclase. Less common uses for this drug include inhibition of embolization from prosthetic heart valves when used in combination with warfarin (the only currently recommended use) and reduction of thrombosis in patients with thrombotic disease when used in combination with aspirin. Alone, dipyridamole has little, if any, benefit in the treatment of thrombotic conditions (102). 

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