Anticholinergic Drugs 

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Anticholinergic Drugs  Important Notes

1. Anticholinergic drugs

  • They inhibit the muscarinic actions of acetylcholine
  • Examples
    • Atropine
    • Scopolamine
    • Propantheline
    • Methantheline

Read And Learn More: Pharmacology Question and Answers

2. Actions of atropine

Atropine

 

3. Drugs causing mydriasis

    • Anticholinergic drugs – atropine
    • Adrenergic drugs – ephedrine, phenylephrine

4. Scopolamine/ Hyosine

    • It is an anticholinergic drug
    • Most effective drug for motion sickness
    • Causes sedation

Anticholinergic Drugs Long Essays

Question 1. Classify anticholinergic drugs. Discuss pharmacological actions, uses & adverse effects of atropine. Mention symptoms of atropine poisoning and the line of treatment.

Answer:

Anticholinergic drugs:

  • Anticholinergic drugs are agents which block the effects of acetylcholine on cholinergic receptors.

Anticholinergic drugs Classification:

1. Natural alkaloids – atropine, hyoscine.

2. Semisynthetic derivatives.

  • Homatropine, atropine mononitrate hyoscine butyl bromide.

3. Synthetic compounds.

  • Mydriatics – cyclopentolate.
  • Antisecretory – antispasmodics.
    • Quaternary compounds – propantheline.
    • Tertiary amines – dicyclomine, pirenzepine.
  • Vasicoselective – Oxybutynin, flavoxate.
  • Anti parkinsonian – trihexyphenidyl, biperiden.

Atropine:

  • It is the chief alkaloid of belladonna.
  • Pharmacological actions.

Anticholinergic Drugs  Atropine Pharmacological Action

Atropine Uses:

  1. Preanaesthetic medication.
    • Atropine is administered 30 min before surgery.
    • This reduces salivary and respiratory secretions which prevent laryngospasm and bradycardia.
  2. As antispasmodic.
    • In diarrhea and dysentery – reduces abdominal pain.
    • Overcomes spasm of the sphincter of Oddi.
    • In nocturnal enuresis – causes urinary retention.
  3. As mydriatic and cycloplegic.
    • Used topically during refractory testing.
    • Used in the treatment of iritis, keratitis, and corneal ulcer.
    • Prevents adhesion between the iris and lens or the iris and cornea.
  4. In organophosphorus poisoning.
  5. In bronchial asthma, peptic ulcer
  6. Used in motion sickness.
  7. Used during labor to produce sedation and amnesia.
  8. Used in myocardial infarction to block vagal bradycardia.
  9. Pulmonary embolism – as it reduces reflex respiratory secretions.
  • High doses lead to atropine poisoning.

Features of atropine poisoning:

  • Palpitation.
  • Excitement, psychotic behavior, ataxia, delirium, hallucination.
  • Hypotension, weak and rapid pulse.
  • Respiratory depression.
  • Dilated pupil, photophobia, blurring of vision.
  • Cardiovascular collapse, convulsions, coma.

Atropine Treatment:

  • Ingested poison was removed by gastric lavage.
  • Use cold sponging or ice bags to reduce body temperature.
  • A drug used is physostigmine – 1 – 3 mg SC or IV, re¬peated 4-6 hourly.
  • It antagonizes control and peripheral effects.

Question 2. Discuss atro¬pine. Mention some atropine substitutes and their uses in therapy.

Answer:

Atropine substitutes:

They aim at producing more selective action on certain functions.

Anticholinergic Drugs  Atropine Substitutes And Their Uses

Anticholinergic Drugs Short Essays

Question 1. Compare atropine and cocaine.

Answer:

Anticholinergic Drugs  Compare Atropine And Cocaine

Question 2. Compare atropine and scopolamine.

Answer:

Anticholinergic Drugs  Compare Atropine And Scopolamine

Anticholinergic Drugs Short Answers

Question 1. Homatropine.

Answer:

Homatropine is an atropine substitute that is used on the eye.

  • Homatropine causes mydriasis & cycloplegia that last for about 6 – 24 hours.
  • They have shorter actions.
  • Homatropine is used in atropine intolerance.
  • Homatropine is formed to overcome the lack of sensitivity of belladonna alkaloids.

Question 2. The rationale of using atropine as pre-anesthetic medication.

Answer:

Atropine is administered 30 minutes before any surgery because.

  • Atropine reduces salivary and respiratory secretion.
    • This prevents laryngospasm.
  • Atropine prevents bradycardia during surgery.
  • Atropine acts as a bronchodilator.
    • This reduces the risk of bronchial asthma related to anaphylactic shock.

Question 3. Enlist six uses of anticholinergic drugs.

Answer:

  1. Preanaesthetic medication – to reduce secretions
  2. Antispasmodic – in diarrhea and colic
  3. Asmydriatric
  4. Parkinsonism – reduces tremors and rigidity
  5. Organophosphorous poisoning – atropine is used
  6. Motion sickness – hyoscine is given 30 minutes before the journey
  7. During labor – hyoscine is used to produce sedation and amnesia

Viva Voce:

  1. Atropine is used in organophosphorus poisoning
  2. Atropine is a CNS stimulant
  3. Scopolamine is CNS depressant

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