[Anticholinergic action of neuroleptics and antidepressives on the guinea pig ileum. Comparison with atropine and pirenzepine].

All the drugs studied here present anticholinergic antimuscarinic dose-dependent activity reversible in front of acetylcholine whether exogenous or released by electrically stimulated Guinea-pig ileum. The classification in decreasing order of anticholinergic power is as follows: atropine, pirenzepine, trimipramine, clozapine, clotiapine , thiotixene , trazodone. Atropine, pirenzepine and probably trazodone act as competitive antagonists, while the other ones have an antagonistic non-competitive action. The action mainly occurs at a postsynaptic level and only trazodone would present a high component of presynaptic action. Our results bear out the hypotheses denying any relation between anticholinergic power and extrapyramidal effects in neuroleptics and between anticholinergic action and antidepressive effect in antidepressants.