Parasympathetic Nervous System (PNS) on Drugs Acting

Parasympathetic Nervous System (PNS) Definition 

• The Parasympathetic Nervous System (PNS) are drugs that mimic or enhance the effects.
• They promote “rest and digest” functions by stimulating muscarinic and nicotinic receptors, leading to effects such as reduced heart rate, increased glandular secretions, and enhanced digestive activity.

Cholinergic Agonists (Parasympathomimetics)

• Mimic acetylcholine, stimulating the PNS.
• Effects: ↓ Heart rate, ↑ Secretions, ↑ Smooth muscle activity.
• Examples: Pilocarpine (glaucoma), Bethanechol (urinary retention).

Cholinesterase Inhibitors

• Prevent acetylcholine breakdown, enhancing its action.
• Uses: Myasthenia gravis (pyridostigmine), Alzheimer’s disease (donepezil).

Anticholinergics (Parasympatholytics)

• Block acetylcholine, inhibiting PNS activity.
• Effects: ↑ Heart rate, Bronchodilation, ↓ Secretions.
• Examples: Atropine (bradycardia), Ipratropium (COPD, asthma).

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