Aim: The 3-azabicyclo(3,3,1)nonanyl-9-α-yl-α-cyclopentyl-α-phenyl-α-glycolate (DM-phencynonate hydrochloride, DMCPG) is a demethylated metabolite of 3-methyl-3-azabicyclo(3,3,1)nonanyl-9-α-yl-α-cyclopentyl-α-phenyl-α-glycolate (phencynonate hydrochloride, CPG). (±)DMCPG had one chiral center and two enantiomers [R(-) and S(+)DMCPG]. Here we carried out a comparative study of the pharmacological profiles of these optical isomers. Methods: Affinity and relative efficacy were tested using a radioligand-binding assay with muscarinic acetylcholine receptors from the rat cerebral cortex. Pharmacological activity was assessed in three individual experiments: (1) potentiating the effect of a subthreshold hypnotic dose of sodium pentobarbital; (2) inhibiting oxotremorineinduced salivation; and (3) inhibiting the contractile response to carbachol. Results: In the competitive binding assay, R(-)DMCPG (K_i=763.75 nmol/L) was 4-and 2-fold more potent than (±)DMCPG (K_i=3186nmol/L) and S(+)DMCPG (K_i=1699 nmol/L) in inhibiting the binding of [3~H]QNB. The R(-) and S (+) configurations showed positive cooperation (n_H>1) with the muscarinic receptor, whereas (±)DMCPG had a negative cooperation (n_H<1) relationship with the muscarinic receptor in a radio-binding assay. Both the R(-) and S(+) configurations could potentiate the effect of sub-threshold hypnotic dose of sodium pentobarbital in a dose-dependent manner (the ED_(50) values were 2.53 and 18.65 mg/kg, respectively), but (±)DMCPG did not display significant central depressant effects at doses from 10 to 29.15 mg/kg (P>0.05). (±)DMCPG and its optical isomers suppressed the guinea pig ileum contractile response to carbachol. The IC_(50) values were 7.78x 10~(-9), 1.88x 10~(-7), and 1.03x10~(-7) nmol/L, respectively. In the anti-salivation study, (±)DMCPG and its enantiomers depressed oxotremorine-induced salivation in a dose-dependent manner, and the order of potency was R(-)DMCPG (ED_(50=0.44 mg/kg)>(±)DMCPG (ED_(50)=2.88 mg/kg)>S(+)DMCPG (ED_(50)=5.05 mg/kg). Conclusion: (±)DMCPG and its optical isomers have differences in their pharmacological potencies as anticholinergic agents, and the R(-) configuration is moreactive than the S(+) configuration. Aim: The 3-azabicyclo (3,3,1) nonanyl-9-α-yl-α-cyclopentyl-α-phenyl- α -glycolate (DMCPG) is a demethylated metabolite of 3-methyl-3 (±) DMCPG had one chiral center and two enantiomers [R (-) - [alpha] -cyclopidine (3,3,1) nonanyl-9-alpha- ) and S (+) DMCPG]. Here we carry out a comparative study of the pharmacological profiles of these optical isomers. Methods: Affinity and relative efficacy were tested using a radioligand-binding assay with muscarinic acetylcholine receptors from the rat cerebral cortex. Pharmacological activity was assessed in three individual experiments: (1) potentiating the effect of a subthreshold hypnotic dose of sodium pentobarbital; (2) inhibiting oxotremorine induced salivation; and (3) inhibiting the contractile response to carbachol. Results: In the competitive binding assay, R (-) DMCPG (K_i = 763.75 nmol / L) was 4-and 2-fold more potent than (±) DMCPG The R (-) and S (+) configurations showed positive cooperation (n_H> 1) with the muscarinic receptor, while (±) DMCPG had a negative cooperation (n_H <1) relationship with the muscarinic receptor in a radio-binding assay. Both the R (-) and S (+) configurations could potentiate the effect of sub-threshold hypnotic dose of sodium pentobarbital in a dose (±) DMCPG did not display significant central depressant effects at doses from 10 to 29.15 mg / kg (± 0.05). (± ) IC50 values ​​were 7.78x 10-9, 1.88x 10-7, and 1.03x10 -7 nmol / L, respectively. In the anti-salivation study, (±) DMCPG and its enantiomers depressed oxotremorine-induced salivation in a dose-dependent manner, and the order of potency was R (-) DMCPG (ED 50 kg)> (±) DMCPG ( ED_ (50) = 2.88 m(±) DMCPG and its optical isomers have differences in their pharmacological potencies as anticholinergic agents, and the R (-) configuration is moreactive than the S (+) configuration.