Atropine

Atropine is a tropane alkaloid that competitively blocks muscarinic acetylcholine receptors. It reduces parasympathetic effects such as secretions and smooth-muscle contraction.

Muscarinic acetylcholine receptor: A G protein-coupled receptor activated by acetylcholine to mediate many parasympathetic effects. Atropine acts by competitively blocking these receptors.
Bradycardia: A slower-than-normal heart rate, often defined in adults as fewer than 60 beats per minute. Atropine can raise heart rate when excessive vagal influence causes symptomatic bradycardia.
Atropa belladonna: A poisonous perennial plant, also called deadly nightshade, that contains tropane alkaloids including atropine. This plant is a major natural source of atropine.
Scopolamine: A tropane alkaloid and muscarinic antagonist used especially to prevent motion sickness and nausea. It shares atropine’s receptor target but has stronger central effects and distinct common uses.
Anticholinergic toxidrome: A syndrome of findings caused by excessive blockade of muscarinic acetylcholine receptors. Severe atropine exposure can produce this characteristic syndrome.
Acetylcholine: A neurotransmitter used by neurons at neuromuscular junctions and throughout the autonomic nervous system. Atropine prevents acetylcholine from activating muscarinic receptors.
Organophosphate poisoning: Toxic exposure to chemicals that inhibit acetylcholinesterase and cause excessive cholinergic signaling. Atropine treats dangerous muscarinic symptoms such as bronchial secretions and bronchoconstriction.
Tropane alkaloid: An alkaloid containing a tropane ring, a bicyclic structure found in several plant-derived compounds. Atropine belongs to this chemical family.
Glycopyrrolate: A synthetic antimuscarinic drug used to reduce secretions and treat certain forms of bradycardia. Unlike atropine, it poorly crosses the blood–brain barrier.
Tachycardia: A faster-than-normal heart rate, commonly defined in adults as more than 100 beats per minute at rest. Atropine can accelerate the heart by reducing parasympathetic restraint.

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