A study of the anticholinergic activity of terfenadine in normal volunteers

The anticholinergic effects of single doses of terfenadine, chlorpheniramine and atropine on salivary flow were compared with those of placebo in a double-blind crossover study in 21 normal adults. Salivary flow was measured immediately before administering study medications and 3 h after dosing, for the evaluation of anticholinergic activity. Mean salivary flow decreased significantly after administration of chlorpheniramine and atropine (P less than 0.01 and P less than 0.001, respectively), and was unchanged by terfenadine and placebo, indicating that terfenadine does not possess detectable anticholinergic activity. Mild drowsiness was reported by 57% and 29% of subjects who received chlorpheniramine and terfenadine, respectively.