Sofpironium bromide (BBI 4000) is an anticholinergic agent used in the study of primary axillary hyperhidrosis (PAH). Sofpironium bromide reduces sweating by inhibiting M3 muscarinic receptors in eccrine glands at the application site. Sofpironium bromide also has a high afnity for the M1, M2, M4 and M5 subtypes.In Vitro: Sofpironium bromide is metabolized mainly through non-enzymatic hydrolysis, and also through oxidative metabolism via CYP2D6 and CYP3A4.In Vivo: Sofpironium bromide exhibits anticholinergic activity by inhibiting the contractile activity of guinea pig ileal tissue in a concentration-dependent manner. In a rat model, Sofpironium bromide reduces footpad sweating induced by Pilocarpine (a muscarinic receptor agonist).