[Anticholinergic properties of oxitropium bromide (Ba 253) and its metabolites]

Anticholinergic properties of oxitropium bromide (Ba 253) were compared with those of atropine and ipratropium bromide (Sch 1000). The metabolites of Ba 253 (Ba 941, BEA 1125), the decomposition product (Ba 250), and the impurity (Ad 187) were also studied. In rat salivary activity, gastric secretion and rabbit gastric-motility, the anticholinergic activities of parenterally administered Ba 253 were 2.3 to 11.8 times and 1 to 2 times stronger than that of atropine and Sch 1000, respectively. The mydriatic and antisecretory actions of Ba 253 (p.o. or i.d.) were 1/7 and 1/47 those of atropine, respectively. In isolated rat stomach, guinea pig gallbladder and ileum, the anticholinergic activity of Ba 253 is similar to that of atropine. Inhalation of Ba 253 aerosol prevented ACh- and histamine-induced cough in guinea pigs, and its potency was 1/5 that of atropine or as the same as that of Sch 1000. In the isolated guinea pig trachea and ileum, the potencies of the anticholinergic activities of Ba 250 and Ad 187 were the same as that of Ba 253, but those of the other metabolites were very weak. These results suggest that the anticholinergic activity of Ba 253 is stronger than that of atropine when parenterally administered, and it cannot distinguish between the subtypes of muscarinic receptors.