Synthesis and antagonistic activity at muscarinic receptor subtypes of some derivatives of diphenidol.

A series of new derivatives, related to diphenidol and to its 2-carbonyl analogue, were designed as antimuscarinic agents. The synthesized compounds were evaluated both as hydrochlorides and as methiodides by functional tests at guinea-pig heart (M(2)), guinea-pig ileum (M(3)) and rabbit vas deferens (putative M(4)). Two derivatives (3a and 5a) showed an M(3)-selective profile similar to that of the reference compounds, though they resulted less potent.