title: An antagonistic activity of etizolam on platelet-activating factor (PAF). In vitro effects on platelet aggregation and PAF receptor binding.
abstract: The antagonistic effect of etizolam, an anti-anxiety drug, on platelet-activating factor (PAF) was investigated in rabbit platelets in vitro. Etizolam inhibited PAF-induced aggregation in a dose-dependent manner, with an IC50 of 3.8 microM, about one tenth that of triazolam (IC50 = 30 microM). At 300 microM, it inhibited both ADP and arachidonic acid-induced aggregation only slightly, while the other anti-anxiety drugs tested had no effect on PAF-induced aggregation even at this concentration. Etizolam and triazolam inhibited the specific binding of 3H-PAF to PAF receptor sites on washed rabbit platelets with IC50 values of 22 nM and 320 nM, respectively. Diazepam and estazolam were inactive even at 1 microM. These results indicate that etizolam is a specific antagonist of PAF.
mesh_terms: D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology; D003975:Diazepam / Q000031:analogs & derivatives* / Q000494:pharmacology; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D010972:Platelet Activating Factor / Q000037:antagonists & inhibitors*; D010974:Platelet Aggregation / Q000187:drug effects*; D010980:Platelet Membrane Glycoproteins; D011817:Rabbits; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled; D014149:Tranquilizing Agents / Q000494:pharmacology*
chemical_list: D014151:Anti-Anxiety Agents; D010972:Platelet Activating Factor; D010980:Platelet Membrane Glycoproteins; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D014149:Tranquilizing Agents; C039351:platelet activating factor receptor; C044610:etizolam; D003975:Diazepam