Himbacine analogs as muscarinic receptor antagonists--effects of tether and heterocyclic variations.

A number of analogs of the natural product himbacine were synthesized employing variations at the heterocyclic unit and the tether that links the heterocyclic unit to the tricyclic motif. Several of these analogs had M(2) affinity and M(1)/M(2) selectivity comparable to those of himbacine. The structural and stereochemical requirements of the heterocyclic unit for muscarinic binding are discussed in the light of these data.

Isopropyl amide derivatives of potent and selective muscarinic M2 receptor antagonists.

Low molecular weight amide derivatives were synthesized and evaluated as M(2) receptor antagonists for the treatment of Alzheimer's disease. Isopropyl amides 19 and 31 are highly potent, selective and low molecular weight M(2) receptor antagonists with structural features different from our clinical candidate 1.

Improving the oral efficacy of CNS drug candidates: discovery of highly orally efficacious piperidinyl piperidine M2 muscarinic receptor antagonists.

In search of a backup M(2) muscarinic receptor antagonist to the previously reported compound 1, we discovered compound (+)-14, which showed superior oral efficacy in animal models. The improvement of oral efficacy was achieved by modulating both the molecular weight and lipophilicity of the lead compounds.

Enhancement of pharmacokinetic properties and in vivo efficacy of benzylidene ketal M(2) muscarinic receptor antagonists via benzamide modification.

We previously reported the initial discovery of a novel class of stabilized benzylidene ketal M(2) receptor antagonists. This paper discusses new analogues consisting of benzamide modifications which not only improved M(2) receptor affinity and selectivity, but also enhanced the pharmacokinetic properties of the series. These changes led to the discovery of a highly potent and selective M(2) antagonist, which demonstrated in vivo efficacy and had good bioavailability in multiple species.

Sulfide analogues as potent and selective M(2) muscarinic receptor antagonists.

We have discovered highly potent, selective sulfide M(2) receptor antagonists with low molecular weight and different structural features compared with our phase I clinical candidate Sch 211803. Analogue 30 showed superior M(2) receptor selectivity profile over Sch 211803. More importantly, this study provided new leads for the discovery of M(2) receptor antagonists as potential drug candidates.

Synthesis and structure-activity relationships of M(2)-selective muscarinic receptor ligands in the 1-[4-(4-arylsulfonyl)-phenylmethyl]-4-(4-piperidinyl)-piperazine family.

The synthesis and muscarinic binding properties of compounds based on the 1-[4-(4-arylsulfonyl)phenylmethyl]-4-(1-aroyl-4-piperidinyl)-piperazine skeleton are described. For compounds, substituted with appropriately configured methyl groups at the benzylic center and at the piperazine 2-position, high levels of selective, M(2) subtype affinity could be obtained, particularly when the terminal N-aroyl residue was ortho-substituted.

Substituted 2-(R)-methyl piperazines as muscarinic M(2) selective ligands.

A novel series of 2-(R)-methyl-substituted piperazines (e.g., 2) is described. They are potent M(2) selective ligands that have >100-fold selectivity versus the M(1) receptor. In the rat microdialysis assay, compound 14 showed significantly enchanced levels of acetylcholine after oral administration.