Quinidine EP Impurity A,(R)-[(2S,4S,5R)-5-ethenyl-1-azabicyclo[2.2.2]oct-2-yl](6-methoxyquinolin-4-yl)methanol,Primary alkaloid of various species of Cinchona (Rubiaceae). Optical isomer of Quinidine. Antimalarial; muscle relaxant (skeletal).,Quinidine