Effect of terfenadine and ranitidine on histamine and suxamethonium wheals.

The effects of the H-1 receptor blocker terfenadine and the H-2 receptor blocker ranitidine have been experimentally tested in wheals induced with histamine and suxamethonium chloride. Ranitidine alone in the standard and a four-fold higher dose did not notably reduce the size of the wheal and flare as compared to placebo. As expected, both parameters were markedly reduced by the H-1 antihistamine terfenadine in full and half-dosage. A combination of the two drugs both in "standard" and modified dosage resulted in the greatest reduction in the wheal and flare. Histamine and suxamethonium-induced wheals reacted in a similar manner to the antihistamines.