Wy 49051 is a potent, orally active H1 receptor antagonist, with IC50 of 44 nM.
Wy 49051 shows great inhibitory effect on H1, producing 92% inhibition of the histamine-induced contraction of the guinea pig ileum at a concentration 100 nM. Wy 49051 is the most potent compound with 700 times the potency of astemazole, 470 times the potency of chlorpheniramine. Wy 49051 also has high affinity for α1 receptor with IC50 of 8 nM[1].
Wy 49051 shows potent activity against histamine-induced lethality in the guinea pig, with ED50 of 1.91 mg/kg by po, 0.70 mg/kg by ip, and 0.01 mg/kg by iv. The duration of action of 24 is also favorable since there is no decrease in oral efficacy up to 18 h posttreatment[1].
[1]. Abou-Gharbia M, et al. New antihistamines: substituted piperazine and piperidine derivatives as novel H1-antagonists. J Med Chem. 1995 Sep 29;38(20):4026-32.