Cholinergic System

Question 1

Cholinergic alkaloids uses

Answer 1

Pilocarpine used for open angle and acute congestive glaucoma , with mydriatics to break adhesion, reverse pupillary dilation and sialogue.

Muscarine - can cause mushroom poisoning and atropine is used for treatment.

Arecoline - muscarine and nicotine action.

Question 2

Uses of reversible anticholinesterase.

Answer 2

Physostigmine - glaucoma and atropine poisoning.

Neostigmine - preferred in myasthenia gravis as done not cross BBB.

Pyridostigmine - preferred over Neo due to longer duration of action.

Edrophonium - For diagnosis of myasthenia gravis and to differentiate between myasthenic and cholinergic crisis and in curare poisoning.

Question 3

Therapeutic uses of anticholinesterase

Answer 3

1) Eye - glaucoma ( osmotic agents, carbonic anhydrase inhibitors and beta blockers and miotics) , reverse pupillary dilation and break adhesion between iris and lens.
2) Myasthenia gravis.
3) Postoperative Urinary Retention and Paralytic Ileus (neostigmine)
4) curare poisoning - edrophonium
5) Belladonna poisoning - physostigmine
6) Alzheimer’s disease - Donepezil, galantamine and rivastigmine.

Echiothiophate is irreversible anticholinesterase which is rarely used in resistant cases of glaucoma.

Question 4

Classification of Antimuscarinic Agents

Answer 4

1. Natural alkaloids : Atropine, scopolamine (hyoscine).
2. Semisynthetic derivatives:
   Hyoscine butyl bromide
   Homatropine (mydriatic)
   Ipratropium bromide, tiotropium bromide (bronchial asthma)
3. Synthetic antimuscarinic agents:
   (a) Used as mydriatic – cyclopentolate, tropicamide
   (b) Used in peptic ulcer – pirenzepine, telenzepine, clidinium, propantheline
   (c) Used as antispasmodic – dicyclomine, valethamate, flavoxate, oxybutynin,
   tolterodine, darifenacin
   (d) Used as preanaesthetic agent – glycopyrrolate
   (e) Used in parkinsonism – benzhexol (trihexyphenidyl), benztropine, biperiden,
   procyclidine

Question 5

Atropine substitute and their uses.

Answer 5

1) Eye - homatropine , cyclopentolate and tropicamide*.

2) Antispasmodics - dicycloamine (dysmenorrhoea) , valethamate (intestinal and urinary colic) , oxybutynins (urologic surgeries) , tolterodine ( overactive detrusor muscle).
3) Bronchodilation - ipratropium bromide and tiotropium bromide*.
4) Peptic ulcer - Pirenzepine
5) Parkinsonism - benzhexol and benztropine.
6) Prea aesthetic medication - glycopyrrolate.
7) Propantheline - Antispasmodics and Peptic ulcer.

Question 6

Therapeutic uses of anti cholinergic drugs.

Answer 6

1) Ophthalmic uses
- mydriatic and cycloplegic (tropicamide)
- prevent adhesion between iris and lens

2) Preanasethetic medication - atropine or glycopyrrolate(peripheral).

3) Sialorrhoea due to heavy metal poisoning and Parkinsonism - glycopyrrolate.

4) COPD and bronchial asthama - Ipratropium bromide and tiotropium bromide

5) Antispasmodics in dysmenorrhoea and abdominal , intestinal colics).

6) Urinary disorders - oxybutynins and flavoxate(urologic surgeries )& tolterodine ( empty bladder).

7) OP Poisoning - atropine

8) Vagolytic - atropine to treat sinus bradycardia and partial heart block.

9) Parkinsonism - benzhexol and benztropine centrally acting.

Question 7

Anticholinergic drugs ganglion blockers

Answer 7

Trimethaphan and nicotine.

Treatment of nicotine addiction - Nicotine chewing gum and transdermal patch, bupropion and varenicline.