Two studies were performed to measure the effects of acrivastine (BW825C), an antihistamine, in combination with alcohol on the central nervous system. In one study acrivastine 8 mg, diphenhydramine 50 mg and alcohol 32 ml were administered alone and in combination and compared with placebo. In a second study terfenadine 60 and 120 mg and acrivastine 4 and 8 mg combined with alcohol 32 ml were compared with placebo and alcohol alone. Each study was a double-blind, randomised cross-over design using twelve healthy volunteers. Adaptive tracking, reaction time, body sway, eye movements and subjective effects were measured at intervals after treatments. Acrivastine 8 mg alone did not affect any of these measures in contrast with diphenhydramine. Acrivastine in combination with alcohol caused significantly more impairment of some of the tests than placebo or alcohol alone, but significantly less than diphenhydramine/alcohol, which also affected more tests. In the second study no significant differences were seen between the effects of alcohol alone and combinations of either terfenadine or acrivastine with alcohol. It was concluded that acrivastine 8 mg alone did not impair CNS performance in the tests used. In combination with alcohol significant impairment was seen, but this was less pronounced than after diphenhydramine/alcohol. The second study failed to demonstrate differences between drug/alcohol combinations and alcohol alone confirming that the effect of acrivastine in combination with alcohol is small.