Glycopyrrolate (Glycopyrrolate bromide) is a muscarinic antagonist used as an antispasmodic, in some disorders of the gastrointestinal tract, and to reduce salivation with some anesthetics.

Glycopyrrolate inhibits EFS-induced contraction of guinea-pig trachea and human airways in a concentration-dependent manner. In competition studies, glycopyrrolate binds human peripheral lung and human airway smooth muscle (HASM) muscarinic receptors with affinities in the nanomolar range (Ki values 0.5–3.6?nM). Glycopyrrolate showed no selectivity in its binding to the M1–M3 receptors. Kinetics studies show that glycopyrrolate dissociates slowly from HASM muscarinic receptors[1].