Antihistamine activity and central effects of WAL 801 CL in man.

The tolerability and antihistaminic activity of WAL801 CL, a new, peripherally acting H1-receptor antagonist, have been evaluated in a double-blind, placebo-controlled, within-subject cross-over study. WAL801 CL 8 mg b.d. was given to 10 healthy volunteers for 15 days. It resulted in a distinct reduction in histamine wheal size and a decreased bronchoconstrictor response to histamine inhalation. No cardiovascular side effects were observed. Transient and slight fatigue was observed in 3 subjects. Psychological tests, such as simple visual reaction time, critical flicker fusion frequency and mood self rating scale, showed that WAL801 CL had no sedative side effects and that it did not alter psychomotor performance.