Epinastine, a nonsedating histamine H1 receptor antagonist, has a negligible effect on HERG channel

Terfenadine and astemizole rarely cause cardiac arrhythmias by suppressing the cardiac rapid delayed rectifier K+ channel encoded by the human ether-a-go-go-related gene (HERG). Epinastine, however, has not been reported to have the adverse effect. We have therefore compared the effects of epinastine, terfenadine and astemizole on HERG channels expressed in Xenopus oocytes. Terfenadine and astemizole suppressed the HERG current with IC50 of 431 nM and 69 nM, respectively. In contrast, 100 mu M epinastine inhibited the HERG current by only 11 +/- 2.1%. These results may provide an explanation for the difference in the cardiotoxity between different nonsedating histamine H-1 receptor antagonists. (C) 1999 Elsevier Science B.V. All rights reserved.