EFFECT OF SR-27417, A NOVEL PAF ANTAGONIST ON ANTIGEN-INDUCED HYPOTENSION IN THE RAT

SR 27417, a potent PAF receptor antagonist, inhibited in a dose-depend ent manner the hypotensive effect of PAF in rats. It protected rats wi th an ED(50) value of 6+/-2 mu g/kg (n = 6), when given i.v., 1 min be fore PAF administration. After i.v. administration, SR 27417 exhibited extended duration of action, a significant protective effect was obse rved up to 48 h after the administration. After i.v. injection, SR 274 17 (0.3, 1 and 3 mg/kg) afforded dose-dependent protection of actively sensitized rats against ovalbumin-induced hypotension but also totall y reversed established antigen-induced hypotension. These results ther efore confirm that PAF plays a major role in anaphylactic shock and su ggest that SR 27417 may be an effective prophylactic as well as a pote nt curative drug in this pathology.