Platelet Activating Factor (PAF) antagonists which comprise the compounds of the formula (I): ##STR1## wherein A is an optionally substituted phenyl or an optionally substituted heterocyclic group; X is methylene group, carbonyl group or thiocarbonyl group; R.sup.1, R.sup.2 and R.sup.3 are independently a lower alkyl group, and their salts are excellent in absorption from the intestinal canal. Among the compounds of the formula (I), those wherein A is an optionally substituted 2,3-dihydro-1-benzoxepin-4-yl group are novel compounds and exhibit excellent PAF antagonism.
血小板活化因子(PAF)拮抗剂包括式(I)的化合物:##STR1## 其中A是可选取的取代苯基或可选取的取代杂环基;X是亚甲基、羰基或
硫代羰基;R.sup.1、R.sup.2和R.sup.3是独立的低碳基,其盐在肠道中的吸收性能极佳。在式(I)的化合物中,其中A是可选取的取代2,3-二氢-1-苯并氧杂-4-基基团的新化合物,表现出优异的PAF拮抗作用。