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Anticholinergic Drugs And Their Actions

26 October, 2020 Arush Emmanuel Michael

Classification Of Anticholinergic Drugs

Anticholinergic Drugs are classified into 3 classes:

  1. Natural alkaloids: Drugs in this category include Atropine and Hyoscine.
  2. Semisynthetic derivatives: Drugs in this category include Ipratropium bromide and Atropine methionitrate.
  3. Synthetic derivatives: These drugs are further classified into Mydriatics, Antisecretory antispasmodics, antiparkinsonian and vasoselective drugs. Antisecretory antispasmodics include quarternary compounds (Isopropamide and Propantheline) and tertiary compounds (Dicyclomine and Valithamate). Mydriatics include cyclopentolate and tropicamide while vasicoselectives include oxybutyrin and flavoxate. Antiparkinsonian anticholinergics mainly pertain to benzhexol and procyclidine. To order drug yo can visit India best online medical shop,3meds.

Pharmacological Actions Of Anticholinergic Drugs

  1. Actions on Central nervous system: The drugs doesn’t penetrate the brain well and acts mainly peripherally having a stimulating effect mainly on areas like the medullary centres- vasomotor, respiratory and vagal. It decreases vestibular excitation leading to its antimotion sickness property. It’s decreases tremors and rigidity in Parkinson’s disease by reducing cholinergic overactivity of the basal ganglia. At high doses, there are hallucinations ,restlessness, delirium and hallucinations followed by respiratory depression and coma.
  2. Actions on Cardiovascular System: Atropine mainly acts to block the M2 receptors and M3 receptors causing an increase in heart rate and tachycardia. The AV conduction increases and the PR interval in the ECG decrease.
  3. Actions on the eyes: On topical instillation, there is mydriasis, abolition of the light reflex and cycloplegia which causes photophobia and blurring of near vision. In near angle glaucoma, this results in increase of intra ocular tension
  4. Actions on blood pressure: Cholinergic impulses not involved in the vascular tone. Atropine has no marked effect on the blood pressure. Tachycardia and stimulation of the vasomotor centre causes an increase in the blood pressure while histamine release and the action of vasodilation results in decrease in the blood pressure.
  5. Action on Smooth Muscles: By blocking the M3 receptors it causes, relaxation of visceral smooth muscles receiving parasympathetic innervation. The bronchioles gets dilated which causes a decrease in airway resistance which is helpful for asthma patients. The stomach and intestine show reduced tone and amplitude of contraction which might cause constipation but mainly used to stop spasms. There is relaxation in the urinary bladder which increases bladder capacity and controls detrusor reflexes.
  6. Action on Glands: There is decreased sweating and saliva secretion which causes difficulty in talking and swallowing. The secretions in stomach and other parts of the gastrointestinal tracts like intestine and the pancreas is also decreased.
  7. The body temperature is increased as well.

Uses Of Anticholinergic Drugs

  1. Antisecretory Uses: Used as a pre anaesthetic medication to prevent laryngospasm and vasovagal attack. They are used in pulmonary embolism to reduce pulmonary secretion as well as to check increased sweating and salivation. Once prescribed drugs for treatment you can now order online medicine from one of the most trusted online pharmacy store 3meds
  2. Antispasmodic uses: It provides symptomatic relief in abdominal cramps, spastic constipation and inflammatory bowel syndrome. It is used to control nervous and drug induced diarrhoea. It also helps to relive urinary frequency and increase bladder capacity.
  3. Used in Bronchial asthma and Chronic Obstructive pulmonary disease to control exacerbations and for regular prophylactic use.
  4. As mydriatic for testing refraction and for performing a fundoscopy. Therapeutically used for treatment of iritis, keratitis and corneal ulcer.
  5. As a cardiac vagolytic to counteract heart block and sinus bradycardia.
  6. Used as adjuvant with levodopa for treatment of parkinsonism.
  7. Hyoscine is most effective anticholinergic for motion sickness and should be given prophylactically before the symptoms appear. The action of the drug lasts for four to six hours and can be administered behind pinna transdermally for three day protection.
  8. Used as an antagonist for muscarinic actions of drugs and poisons.


Side effects of anticholinergic drugs are common and toxicity may manifest as belladona poisoning if the patient overdoses or consumes seeds or berries of belladona. Children are highly susceptible to this toxicity. The person suffers from dry mouth, scarlet rash, fever, dilated pupils, photophobia, blurring of vision, convulsions, respiratory depression and coma. the ingested poison is removed through a gastric lavage with tannic acid. The patients vital should be checked and he/she should be kept in a quite dark room. Physostigmine should be administered and cold sponging ice baths should be given to reduce body temperature.