A placebo controlled comparison of the effects of pirenzepine and amitriptyline on the tyramine pressor test in healthy volunteers.

The possibility of an interaction between pirenzepine, an antimuscarinic drug structurally similar to the tricyclic antidepressants, and sympathomimetic agents was investigated in a group of healthy volunteers. The effect of pirenzepine on response to intravenous tyramine was compared with that of placebo and amitriptyline. The mean dose of tyramine required to elevate systolic blood pressure by 30 mm Hg was 5.0 mg (+/- s.d. 0.8) after placebo, 5.1 mg (+/- 1.0) after pirenzepine and 11.3 mg (+/- 1.8) after amitriptyline. These results suggest that pirenzepine will not potentiate the effects of concurrently administered sympathomimetic drugs.