The effect of pirenzepine on the functions of human platelets

Despite the very high chemical similarity of pirenzepine (P) to the selected tricyclic antidepressive drugs (TCAD) (imipramine, desimipramine, nortriptyline and amitriptyline), P has a distinctly different effect on platelets, in particular, on serotonin uptake and platelet aggregation. Using two groups of nine healthy volunteers, mean age 27.7 and 27.5 years, respectively, assessment of the two indicators in vitro helped us to eliminate the possibility of a drug induced defect of the two thrombocyte functions, i.e. their aggregation and serotonin uptake. There is therefore, no reason to fear the danger of decreased hemocoagulation in ulcer patients treated with P for gastrointestinal hemorrhage. The results obtained in vivo using two tests which showed the level of platelet activation associated with release of a specific platelet protein (beta-thromboglobulin in platelet-poor plasma) and malondialdehyde in thrombocyte-rich plasma ruled out any changes, specifically their increase, and have disproved any kind of stimulating activity of P on thrombocyte reactivity.