Question

A passer-by notices that Geoffrey is in distress and calls 000. When the paramedics arrive, as part of their treatment they administer atropine (2 mg IV) repeated every 5 minutes for 20 minutes.

Question:

b). Briefly discuss the mechanism of action of atropine and identify why repeated dosing is required for a 20 minute duration. (Maximum 100 words)

Answer 1

Ans) b) Atropine: Anticholinergic agent

Mechanism of action of Atropine:

- Blocks the action of acetylcholine as a competitive edge antagonist at muscarinic receptor sites and smooth muscle, secretory glands in the CNS.

- It works by blocking parasympathetic response and allowing sympathetic response to take over.

Indications of Atropine:

• IM: Given preoperatively to decrease oral and respiratory secretions.

• IV: Treatment of sinus bradycardia and heart block.

• PO: Adjunctive therapy in the management of peptic ulcer and irritable bowel syndrome.

• IV: Reversal of adverse muscarinic effects of anticholinesterase agents (neostigmine, physostigmine, or pyridostigmine).

• IM, IV: Treatment of anticholinesterase (organophosphate pesticide) poisoning.

• Inhalation: Treatment of exercise-induced bronchospasm

Administration of Atropine:

- Initially 1.5 mg.

- Doses should be doubled every 5 minutes until signs of muscarinic excess - clearing of bronchial secretions, bronchospasm and adequate oxygenation.

During adult cardiopulmonary resuscitation (CPR): Resuscitation drugs may be administered intravenously by bolus injection into a peripheral vein, followed by an injection of 20 mL IV fluid. Elevate the extremity for 10 to 20 seconds to facilitate drug delivery to the central circulation. Although peak drug concentrations are lower when drugs are administered via peripheral vs. central sites, the establishment of peripheral access does not require interruption of CPR. Drugs generally reach the central circulation within 1 to 2 minutes when administered peripherally but require less time when given via central venous access.