4-damp 4-damp 4-damp (1,1-dimethyl-4-diphenylacetoxypiperidinium iodide) is a selective muscarinic acetylcholine receptor (machr) m3 antagonist. it is also able to antagonize m1 receptors but "prefers" m3. it competitively binds to the acetylcholine binding site on machrs, causing right-ward shift in the dose response curves for machr agonists. 4-damp names preferred iupac name 4--1,1-dimethylpiperidin-1-ium iodide other names 4-(2,2-diphenylacetoxy)-1,1-dimethylpiperidin-1-ium iodide identifiers cas number 1952-15-4 y 3d model (jsmol) interactive image chemspider 2282596 pubchem cid 3014059 unii cp6gvv66rg y comptox dashboard (epa) dtxsid40941281 inchi inchi=1s/c21h26no2.hi/c1-22(2)15-13-19(14-16-22)24-21(23)20(17-9-5-3-6-10-17)18-11-7-4-8-12-18;/h3-12,19-20h,13-16h2,1-2h3;1h/q+1;/p-1key: wwjhrscuaqpfqo-uhfffaoysa-m smiles .c1(c)ccc(cc1)oc(=o)c(c1=cc=cc=c1)c1=cc=cc=c1 properties chemical formula c21h26ino2 molar mass 451.348 g·mol−1 appearance white to beige powder except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). infobox references