Israpafant (Y-24180) is a drug which acts as a selective antagonist for the platelet-activating factor receptor,[1] and was originally developed for the treatment of asthma.

[2] Its chemical structure is a thienotriazolodiazepine, closely related to the sedative benzodiazepine derivative etizolam.

However israpafant binds far more tightly to the platelet-activating factor receptor, with an IC50 of 0.84nM for inhibiting PAF-induced human platelet aggregation (compared to etizolam's IC50 of 998nM at this target), while it binds only weakly to benzodiazepine receptors, with a Ki of 3680nM.

[3] Israpafant has been found to inhibit the activation of eosinophil cells,[4][5][6] and consequently delays the development of immune responses.

It has also been shown to have anti-nephrotoxic properties,[7] and to mobilize calcium transport.