Darifenacin(UK88525) is a selective M3 muscarinic receptor antagonist with pKi of 8.9.
IC50 value: 8.9 (pKi)
Target: M3 receptor
in vitro: Darifenacin exerts non-parallel rightward displacement of the agonist curve and also significant depression of the maximum response (+)-cis-Dioxolane produced concentration-dependent contraction of the isolated bladder of rat.  Darifenacin produces a concentration dependent increase in R123 (P-gp probe) accumulation in MDCK cells. Darifenacin stimulates ATPase activity in P-gp membrane in a clear concentration dependent response manner with an estimated ED50 value of 1.6?μM. Darifenacin (100 nM) shows a significantly greater permeability for darifenacin in the basolateral to apical direction resulting in an efflux ratio in BBMEC monolayers of approximately 2.6 .
in vivo: Darifenacin produces dose-dependent inhibition of amplitude of volume-induced bladder contractions(VIBCAMP), producing 35% inhibition at dose of 283.3 nmol/kg and maximal inhibition of approximately 50–55% [1]. Darifenacin (0.1 mg/kg i.v.) reduces bladder afferent activity in both Aδ and C fibers in female Sprague-Dawley rats, the decrease in afferent spikes in C fibers may be more pronounced than that in Aδ fibers.

mAChR
Diphenmanil methylsulfate
Fesoterodine fumarate
Flavoxate hydrochloride
Gallamine Triethiodide
Glycopyrrolate
Homatropine Bromide
Ipratropium bromide
Irsogladine
L-Hyoscyamine
mAChR-IN-1
Methscopolamine bromide
Otilonium bromide
Oxybutynin