SUN 1334H

SUN 1334H is a potent, orally active, highly selective H1 receptor antagonist, with K_i of 9.7 nM. IC50 & Target: Ki: 9.7 nM (H1 receptor)^[1] In Vitro: SUN-1334H causes potent inhibition of histamine induced contractions of isolated guinea-pig ileum with an IC₅₀ (half the maximal inhibitory concentration) of 0.198 μM. In CHO-K1/hERG cells, SUN-1334H does not modulate hERG K⁺-currents at concentrations as high as 100 μM^[1]. SUN-1334H, cetirizine and hydroxyzine cause comparable inhibition of NLF leukocytes, IL-4 and total protein concentrations^[2]. In Vivo: SUN-1334H potently inhibits histamine-induced bronchospasm over 24 hours following oral administration and completely suppresses histamine-induced skin wheal in beagle dogs and ovalbumin-induced rhinitis in guinea pigs^[1]. In skin allergy models, SUN-1334H shows potent reduction of passive and active cutaneous anaphylactic reactions. In central nervous system side effects models, SUN-1334H, desloratadine and fexofenadine are devoid of any significant effects^[2].