Influence of "selective" antimuscarinic agents on gastric acid secretion and motility.

: The effects of antimuscarinic agents, claimed as acting selectively on gastric acid secretion (pirenzepine) or gut motility (secoverine) or lacking selectivity (atropine and ipratropium bromide), were assayed on both functions by means of two simple experimental models: the gastric acid secretion induced by pylorus ligation and the gastric emptying of a high viscosity meal in the conscious rat. When the same experimental conditions were used in the two tests (i.v. route; duration of the test: 1 hr) we found that pirenzepine was not more selective than atropine on either function while ipratropium bromide was 16 times more selective for gastric secretion and secoverine 2.6 times more selective for gastric motility. Even if routes of administration and times of duration were different between the two tests, similar results were obtained. It was concluded that, when compared to atropine, in our in vivo experimental conditions pirenzepine and secoverine show a scant if any selectivity for either function, while, paradoxically, a sharp selectivity for gastric secretion is shown by the bronchodilator ipratropium bromide.