A dose-ranging study of the effects of mequitazine on actual driving, memory and psychomotor performance as compared to dexchlorpheniramine, cetirizine and placebo.
BACKGROUND
Mequitazine is a so-called 'non-sedative' second-generation antihistamine even though it has never been firmly established that this drug's sedative potential actually differs from that of the 'sedative' first-generation antihistamines.


OBJECTIVE
The present study compares the sedative effects of three doses of mequitazine on actual driving, psychomotor performance and memory with those of a first- and a second-generation antihistamine.


METHODS
Eighteen healthy volunteers received on separate days a single dose of 5, 10 and 15 mg mequitazine, 10 mg cetirizine, 6 mg dexchlorpheniramine and placebo. Drug effects were assessed using two actual driving tests (highway-driving test and car-following test), cognitive and psychometric tests (tracking, divided attention, memory, reasoning and critical flicker fusion), pupil size and questionnaires.


RESULTS
Highway-driving data revealed an overall effect of Treatment on the standard deviation of lateral position (SDLP). Dexchlorpheniramine impaired driving performance as indicated by a significant rise in SDLP. Mequitazine significantly increased SDLP in a dose-related manner, but the separate dose effects failed to reach statistical significance. Divided attention performance was also affected by Treatment. Reaction time (RT) during mequitazine treatments increased in a dose-related manner and significantly differed from placebo at the highest dose. Subjects reported to be less alert after treatment with dexchlorpheniramine. Cetirizine did not affect performance in any of the tasks.


CONCLUSIONS
It was concluded that mequitazine is mildly sedating. The effects of mequitazine are comparable to those of other second-generation antihistamines, in that it causes mild driving impairment, particularly at higher doses.
Experimental Psychopharmacology Unit, Brain and Behaviour Institute, Faculty of Psychology, Maastricht University, The Netherlands. e.theunissen@psychology.unimaas.nl
E L
EL
Theunissen
A
A
Vermeeren
A C M
AC
van Oers
I
I
van Maris
J G
JG
Ramaekers
D000328:Adult; D001334:Automobile Driving; D017332:Cetirizine / Q000494:pharmacology; D002744:Chlorpheniramine / Q000494:pharmacology; D003071:Cognition / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D006634:Histamine H1 Antagonists / Q000494:pharmacology*; D006801:Humans; D008297:Male; D010640:Phenothiazines / Q000494:pharmacology*; D011594:Psychometrics; D011597:Psychomotor Performance / Q000187:drug effects*; D018709:Statistics, Nonparametric
D006634:Histamine H1 Antagonists; D010640:Phenothiazines; C018904:dexchlorpheniramine; D002744:Chlorpheniramine; C006069:mequitazine; D017332:Cetirizine