Zenidolol (hydrochloride)

Zenidolol (ICI-118551) hydrochloride is a highly selective β2 adrenergic receptor antagonist, with K_is of 0.7, 49.5 and 611 nM for β2, β1 and β3 receptors, respectively. IC50 & Target:Ki: 0.7nM (β2 receptor), 49.5 nM (β1 receptor), 611 nM (β3 receptor)^[4] In Vitro:Zenidolol (ICI-118551) hydrochloride inhibits cAMP accumulation with IC₅₀ of 1.7 μM in IMCD cells^[1]. Zenidolol (ICI-118551; 10 μM) hydrochloride induces a prominent vasorelaxation of norepinephrine (NE)-precontracted PA but not AO^[2]. In failing human heart, Zenidolol (ICI-118551) has significant effects on beat duration, with time-to-peak contraction and time-to-90% relaxation reduced compared with basal contraction. Negative Inotropic Effect of Zenidolol (ICI-118551) Is Not cAMP-Related. Overexpression of β2AR in rabbit myocytes enhances negative inotropic effects of Zenidolol (ICI-118551)^[3]. In Vivo:Zenidolol (ICI-118551; 0.2 mg/kg) hydrochloride injected into the jugular vein of the mice, reduces systolic pressure in the pulmonary circuit but not systemic arterial pressure^[2].