Atropine

Chemical formula: C₁₇H₂₃NO₃  Molecular mass: 289.369 g/mol  PubChem compound: 174174

Mechanism of action

Atropine is an antimuscarinic agent which competitively antagonizes acetylcholine at postganglionic nerve endings, thus affecting receptors of the exocrine glands, smooth muscle, cardiac muscle and the central nervous system.

Pharmacodynamic properties

Pharmacodynamic effects

Peripheral effects include tachycardia, decreased production of saliva, sweat, bronchial, nasal, lachrymal and gastric secretions, decreased intestinal motility and inhibition of micturition.

Atropine increases sinus rate and sinoatrial and AV conduction. Usually heart rate is increased but there may be an initial bradycardia.

Atropine inhibits secretions throughout the respiratory tract and relaxes bronchial smooth muscle producing bronchodilatation.

Pharmacokinetic properties

Absorption

Atropine is readily absorbed from the gastro-intestinal tract and mucous membranes. It is absorbed from the eye and to a lesser extent through intact skin.

Following intravenous administration, the peak increase in heart rate occurs within 2 to 4 minutes. Plasma levels after intramuscular and intravenous injection are comparable at one hour.

Distribution

Peak plasma concentrations of atropine after intramuscular administration are reached within 30 minutes, although peak effects on the heart, sweating and salivation may occur nearer one hour after intramuscular administration. Atropine is distributed widely throughout the body and crosses the blood brain barrier.

Biotransformation

Atropine is completely metabolised in the liver and is excreted in the urine as unchanged drug and metabolites.

Elimination

The elimination half life is about 2 to 5 hours. Up to 50% of the dose is protein bound. It disappears rapidly from the circulation.

About 50% of the dose is excreted within 4 hours and 90% in 24 hours in the urine, about 30 to 50% as unchanged drug.

Preclinical safety data

Non-clinical data reveal no special hazard for humans based on studies of safety pharmacology, repeated dose toxicity, genotoxicity and limited studies on carcinogenic potential. No adequate studies of reproductive toxicity have been performed.

Related medicines

© All content on this website, including data entry, data processing, decision support tools, "RxReasoner" logo and graphics, is the intellectual property of RxReasoner and is protected by copyright laws. Unauthorized reproduction or distribution of any part of this content without explicit written permission from RxReasoner is strictly prohibited. Any third-party content used on this site is acknowledged and utilized under fair use principles.