Israpafant (Y-24180) is a drug which acts as a selective antagonist for the platelet-activating factor receptor, and was originally developed for the treatment of asthma. 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. Israpafant has been found to inhibit the activation of eosinophil cells, and consequently delays the development of immune responses. It has also been shown to have anti-nephrotoxic properties, and to mobilize calcium transport.
^Hozawa, S (1995). "Effects of a PAF antagonist, Y-24180, on bronchial hyperresponsiveness in patients with asthma.". American Journal of Respiratory and Critical Care Medicine. 152 (4): 1198–1202. PMID7551370. doi:10.1164/ajrccm.152.4.7551370.
^Takehara, S. (1990). "Pharmacological actions of Y-24180, a new specific antagonist of Platelet Activating Factor (PAF): II. Interactions with PAF and benzodiazepine receptors". Prostaglandins. 40 (6): 571–583. doi:10.1016/0090-6980(90)90002-D.
^Komatsu, H; Amano, M; Yamaguchi, S; Sugahara, K. "Inhibition of activation of human peripheral blood eosinophils by Y-24180, an antagonist to platelet-activating factor receptor". Life Sci. 65 (13): PL171–6. PMID10503965. doi:10.1016/s0024-3205(99)00385-9.
^Mizuki, M; Komatsu, H; Akiyama, Y; Iwane, S; Tsuda, T (1999). "Inhibition of eosinophil activation in bronchoalveolar lavage fluid from atopic asthmatics by Y-24180, an antagonist to platelet-activating factor". Life Sciences. 65 (20): 2031–9. PMID10579457. doi:10.1016/s0024-3205(99)00470-1.
^Satoh, T; Tahara, E; Yamada, T; Watanabe, C; Itoh, T; Terasawa, K; Nagai, H; Saiki, I (Feb 2000). "Differential effect of antiallergic drugs on IgE-mediated cutaneous reaction in passively sensitized mice". Pharmacology. 60 (2): 97–104. PMID10657759. doi:10.1159/000028353.
^Kawaguchi, A; Sugimoto, K; Fujimura, A (Jan 2001). "Preventive effect of platelet-activating factor antagonist, Y-24180, against cyclosporine-induced acute nephrotoxicity". Life Sciences. 68 (10): 1181–90. PMID11228102. doi:10.1016/s0024-3205(00)01028-6.