Comparative study of the peripheral and central effects of terfenadine and cetirizine 2 HCl.

The histamine cutaneous reactivity of healthy volunteers was measured after a single oral intake of placebo, terfenadine 60 mg and 180 mg, and cetirizine 2 HCl 10 mg. Central side effects were evaluated by Visual Analog Scales for drowsiness and movement coordination. The anti-H1 cutaneous effect of cetirizine 2 HCl proved to be significantly more rapid, more pronounced, and longer lasting than that of terfenadine 60 mg. Cetirizine and terfenadine 180 mg were equipotent. The Visual Analog Scales for central nervous system effects did not show any difference between cetirizine, terfenadine, and placebo.