IT IS A POTENT AND RAPIDLY ACTING ANTIMUSCARINIC LACKING CENTRAL EFFECTS. ALMOST EXCLUSIVELY USED FOR PRE-ANAESTHETIC MEDICATION AND DURING ANAESTHESIA. GLYCOPYRROLATE, LIKE OTHER ANTICHOLINERGIC (ANTIMUSCARINIC) AGENTS, INHIBITS THE ACTION OF ACETYLCHOLINE ON STRUCTURES INNERVATED BY POSTGANGLIONIC CHOLINERGIC NERVES AND ON SMOOTH MUSCLES THAT RESPOND TO ACETYLCHOLINE BUT LACK CHOLINERGIC INNERVATION. THESE PERIPHERAL CHOLINERGIC RECEPTORS ARE PRESENT IN THE AUTONOMIC EFFECTOR CELLS OF SMOOTH MUSCLE, CARDIAC MUSCLE, THE SINOATRIAL NODE, THE ATRIOVENTRICULAR NODE, EXOCRINE GLANDS, AND, TO A LIMITED DEGREE, IN THE AUTONOMIC GANGLIA. THUS, IT DIMINISHES THE VOLUME AND FREE ACIDITY OF GASTRIC SECRETIONS AND CONTROLS EXCESSIVE PHARYNGEAL, TRACHEAL, AND BRONCHIAL SECRETIONS. GLYCOPYRROLATE ANTAGONIZES MUSCARINIC SYMPTOMS (E.G., BRONCHORRHEA,
BRONCHOSPASM, BRADYCARDIA, AND INTESTINAL HYPERMOTILITY) INDUCED BY CHOLINERGIC DRUGS SUCH AS THE ANTICHOLINESTERASES. THE HIGHLY POLAR QUATERNARY AMMONIUM GROUP OF GLYCOPYRROLATE LIMITS ITS PASSAGE
ACROSS LIPID MEMBRANES, SUCH AS THE BLOOD-BRAIN BARRIER, IN CONTRAST TO ATROPINE SULFATE AND SCOPOLAMINE HYDROBROMIDE, WHICH ARE NON-POLAR TERTIARY AMINES WHICH PENETRATE LIPID BARRIERS EASILY.