Comparison of the effects of binodaline and amitriptyline on peripheral autonomic functions in healthy volunteers

Twelve healthy male volunteers participated in five experimental sessions separated by weekly intervals. At the beginning of each session the subjects received one single oral dose of the following drugs, according to a double-blind, balanced cross-over design: binodaline hydrochloride (50 mg or 100 mg); amitriptyline hydrochloride (50 mg or 100 mg); lactose placebo. Salivation and resting pupil diameter were assessed before and 2 h after the ingestion of the drugs; baseline sweating, carbachol- or phenylephrine-evoked sweating were measured 2 h following drug taking. Binodaline, like placebo, had little effect on salivary output, whereas amitriptyline caused a dose-dependent decrease in salivation. None of the drugs caused any significant change in resting pupil diameter or in baseline sweating. Carbachol-evoked sweating did not differ significantly following the ingestion of binodaline or placebo; on the other hand responses to carbachol were significantly reduced following amitriptyline. Phenylephrine-evoked sweating was reduced by both binodaline and amitriptyline. The lack of effect of binodaline on salivation, resting pupil diameter, baseline and carbachol-evoked sweating is in agreement with the results of animal experiments indicating the lack of an interaction of this drug with cholinergic mechanisms. The reduction in phenylephrine-evoked sweating would be indicative of an alpha-adrenoceptor blocking property of this drug.