UH-AH 37, an ileal-selective muscarinic antagonist that does not discriminate between M2 and M3 binding sites

The novel antimuscarinic compound UH-AH 37 (6-chloro-5,10-dihydro-5-[(1-methyl-4-piperidyl)acetyl]-11H- dibenzo-[b, e][1,4]diazepine-11-one hydrochloride) showed a 14-fold higher affinity for ileal than for atrial muscarinic receptors. In receptor binding studies UH-AH 37 showed no marked selectivity for either atrial, glandular or ileal muscarinic binding sites. Moreover, it did not reveal binding heterogeneity in membranes from ileal smooth muscle. These result indicate that UH-AH 37 possesses a unique and novel selectivity profile.