4-DAMP (E4774-GRP)

4-DAMP (4-diphenyl-acetoxy-N-methyl-piperidine) (4-DAMP methiodide) is a selective antagonist of M3 type muscarinic acetylcholine receptors (M3-mAChR) with a pKi of 9.3. It also has a high affinity for the closely-related M5 receptor with a pKi of 8.9. It is routinely used to study the regulation and functions of the M3 receptor.