Effects of cetirizine and epinastine on the skin response to histamine iontophoresis

Epinastine and cetirizine are second-generation, nonsedating and long-lasti ng antihistamines that art: now frequently used for the allergic disorders. We have examined the inhibitory effects of these two drugs on the histamin e-induced flare and wheal responses using iontophoresis at 1, 2, 4, 8 and 2 4 h after the oral administration by a double-blind, cross-over and placebo -controlled study. Both cetirizine and epinastine significantly inhibited t he histamine-induced flare and wheal responses at 2 h after the oral admini stration when compared with placebo. The inihibitory effects of cetirizine and epinastine on the flare response lasted long until at 24 h, however, ep inastine was less potent than cetirizine. The inhibitory effects on the whe al response was also clearly and significantly evident at 2-8 h by cetirizi ne and epinastine. At 24 h cetirizine only shelved the significant inhibiti on on the histamine-induced wheal response. In contrast, epinastine seemed to exhibit the inhibitory capacity earlier than did cetirizine. The inhibit ory action of the drugs on the histamine-induced wheal response peaked at 4 h after the oral administration. The histamine-induced itch sensation was also markedly or completely suppressed at 2-8 h by the drugs. Thus, both dr ugs exhibited the potent. and long-lasting antihistamine activity on the sk in responses induced by histamine iontophoresis, (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.