Comparative anticholinergic activity of oxaprotiline and amitriptyline

As part of a double‐blind multicenter trial comparing oxaprotiline with amitriptyline and placebo in 308 outpatients with moderate depression, objective (salivary flow) and subjective (dry mouth, blurred vision/visual disorder, and constipation) determinants of anticholinergic activity were assessed. Both active treatments, but not placebo, induced approximately a 40% reduction in salivary flow after one week of treatment with 75 mg/day h.s. Whereas amitriptyline caused a further reduction (26%) in salivary flow by the end of the trial (week 5), no such reduction was noted with oxaprotiline. With regards to subjective complaints, more patients experienced dry mouth and blurred vision/visual degree of sedation is related to the degree of anticholinergic effects per se. Rather, the sedation may be related to a specific anticholinergic effect, such as changes in salivary flow.