Effect of FR128998, a novel PAF receptor antagonist, on endotoxin-induced disseminated intravascular coagulation.

This study aimed to evaluate the effect of FR128998, (1s,6s)-1-benzyl-10-(3-pyridyl-methyl)-7-thia-10-azaspiro [5,6]-dodecan-11-one 7,7-dioxide hydrochloride, a novel platelet activating factor (PAF) receptor antagonist, on endotoxin lipopolysaccharide-induced disseminated intravascular coagulation in rats. Experimental disseminated intravascular coagulation was induced by an infusion of lipopolysaccharide at 0.25 mg/kg/h for 4 h. Simultaneous infusion of FR128998 (0.25 and 1.0 mg/kg/h) with lipopolysaccharide dose dependently inhibited thrombocytopenia, but not leukopenia. The changes in coagulation parameters of disseminated intravascular coagulation, i.e., prolongation of activated partial thromboplastin time and elevated levels of fibrinogen/fibrin degradation products, were also prevented by the treatment with FR128998. In addition, FR128998 attenuated the increase in serum tumor necrosis factor (TNF) which appeared during the initial stage of disseminated intravascular coagulation. FR128998 (10 microM) also inhibited the TNF production by peripheral blood leukocytes or alveolar macrophages stimulated by lipopolysaccharide in vitro. Furthermore, TNF production induced by PAF itself in vitro was also inhibited in the presence of FR128998. These data indicate that PAF plays a pivotal role in the development of disseminated intravascular coagulation via TNF production.