pharmacology of Anticholinergics: Atropine

Atropine deadly nightshade Atropa belladonna alkaloid molecule Medicinal drug and poison also found in Jimson weed Datura stramonium and mandrake Mandragora officinarum Skeletal formula
#Atropine deadly nightshade Atropa belladonna alkaloid molecule Medicinal drug and poison also found in Jimson weed Datura stramonium and mandrake Mandragora officinarum Skeletal formula

Atropine is a medication that belongs to a class of drugs known as anticholinergics or parasympatholytics. It has a variety of uses in medicine, ranging from treating certain types of poisonings to reducing saliva production during surgery. Below is a comprehensive overview of atropine:

Mechanism of Action:

Atropine works by blocking the action of acetylcholine at muscarinic receptors in the parasympathetic nervous system. This results in inhibition of parasympathetic nerve impulses, leading to increased heart rate, relaxation of smooth muscles, and dilation of the pupils.


  • Absorption: Atropine is well absorbed from the gastrointestinal tract and through mucous membranes.
  • Distribution: It is distributed throughout the body, including the central nervous system.
  • Metabolism: Atropine is partially metabolized in the liver.
  • Excretion: It is excreted in urine, with a small amount excreted unchanged.

Adverse Effects:

  • Dry Mouth: Due to reduced saliva production.
  • Blurred Vision and Photophobia: Resulting from pupil dilation.
  • Increased Heart Rate: Especially at higher doses.
  • Urinary Retention: Due to relaxation of the bladder.
  • Constipation: Resulting from reduced gastrointestinal motility.
  • Confusion and Hallucinations: Especially in the elderly and at higher doses.

Clinical Uses:

  • Bradycardia: Used to increase heart rate in cases of bradycardia (slow heart rate).
  • Organophosphate Poisoning: Atropine is a key treatment for poisoning by organophosphate insecticides and nerve agents.
  • Pre-anesthetic Medication: Used to reduce saliva and secretions in the respiratory tract.
  • Asthma: Atropine can help to relax the muscles in the airways, making breathing easier.
  • Ophthalmology: Used to dilate the pupils for eye examinations.


  • Glaucoma: Atropine can increase intraocular pressure, making it dangerous for people with glaucoma.
  • Prostatic Hyperplasia: Can increase the risk of urinary retention.
  • Obstructive Gastrointestinal Conditions: Such as pyloric stenosis.

Drug Interactions:

  • Other Anticholinergics: The effects of atropine can be enhanced when used with other anticholinergic drugs, increasing the risk of side effects.
  • Antihistamines and Antidepressants: Some of these medications have anticholinergic effects and can increase the risk of side effects when used with atropine.

Dosage and Administration:

  • The dosage of atropine depends on the condition being treated, the route of administration, and the age and health of the patient.
  • It can be administered orally, intravenously, intramuscularly, or topically.


  • Patients receiving atropine should be monitored for signs of overdose, such as extreme dry mouth, blurred vision, and hallucinations.
  • Heart rate and blood pressure should be monitored, especially when used to treat bradycardia.

Antidote for Overdose:

  • In cases of atropine overdose, an antidote called pralidoxime may be used, along with supportive care.


Atropine is a versatile medication with a wide range of uses in medicine. While it can be highly effective for treating certain conditions, its use is associated with a variety of side effects due to its anticholinergic properties. Appropriate dosing, careful monitoring, and awareness of contraindications and potential drug interactions are essential to ensure safe and effective use.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always seek the advice of a healthcare provider with any questions regarding a medical condition.

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