Scopolamine is a belladonna alkaloid with anticholinergic effects indicated for the treatment of nausea and vomiting associated with motion sickness and postoperative nausea and vomiting (PONV). It can be found under the brand names Donnatal, Phenohytro, and Transderm Scop. Acetylcholine (ACh) is a neurotransmitter that can signal through ligand-gated cation channels (nicotinic receptors) and G-protein-coupled muscarinic receptors (mAChRs). ACh signalling via mAChRs located in the central nervous system (CNS) and periphery can regulate smooth muscle contraction, glandular secretions, heart rate, and various neurological phenomena such as learning and memory. mAChRs can be divided into five subtypes, M1-M5, expressed at various levels throughout the brain. Also, M2 receptors are found in the heart and M3 receptors in smooth muscles, mediating effects apart from the direct modulation of the parasympathetic nervous system. While M1, M3, and M5 mAChRs primarily couple to Gq proteins to activate phospholipase C, M2 and M4 mainly couple to Gi/o proteins to inhibit adenylyl cyclase and modulate cellular ion flow. This system, in part, helps to control physiological responses such as nausea and vomiting. The significance of these observations to scopolamine's current therapeutic indications of preventing nausea and vomiting is unclear but is linked to its anticholinergic effect and ability to alter signalling through the CNS associated with vomiting. Possible side effects of using scopolamine may include disorientation, dry mouth, drowsiness, and sweating.

Scopolamine Pathway References