1. Anticholinergic drugs
Dr. S. Parthasarathy
MD., DA., DNB, MD (Acu), Dip. Diab. DCA, Dip. Software statistics-
PhD ( physiology), IDRA

2. What are they ?
Anticholinergic drugs competitively antagonize the effects (parasympathetic) of the neurotransmitter acetylcholine at cholinergic postganglionic sites designated as muscarinic receptors
Inverse agonist ??
Change the receptor to inactive state !!

3. Muscarinic cholinergic receptors are present in the heart, salivary glands, and smooth muscles of the gastrointestinal and genitourinary tract.
Anticholinergic means – anti muscarinic
Nicotinic means – ganglion blockers like hexamethanonium – not discussed

4. Nicotine and muscarine – alkaloids

5. Why nicotinic blockers don’t block neuromuscular junction ??
Nicotinic receptors – Nn
Nicotinic receptors – Nm
Curare in high doses can also block ganglion
Hexamethonium in high doses can also block NMJ

6. Receptor subtypes M1 M2 M3 M4 M5 location CNS Stomach Heart Airway
Salivary
Endothelium
heart
Effects
H+ ion secretion
Others
Constrict
Brady
Vasodilation
Salivation
bronchoconstrict
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7. Classification Natural Atropine , scopolamine Semisynthetic
Homatropine , ipratropium
Synthetic
Propantheline ,Oxyphenonium, clidinium, Pipenzolatemethylbromide, Isopropamide, Glycopyrrolate. --- numerous

8. Tertiary amines
Atropine , scopolamine
Quarternary ammonium
Glycopyrrolate

9. The three musketeers – similarity
Atropine
Glycopyrrolate

10. Atropine Tropic acid + tropine Scopolomine Glycopyrollate
Tropic acid with scopine ( hyoscine)
Glycopyrollate
Quarternary ammonium compound

11. Atropine Alkaloid of atropa belladona Deadly nightshade
1880s – reduce vagal tone in anaesthesia
1915 – inhibit secretions in anesthesia

12. Action and uses Decrease secretions
when do we utilize this property ??
Children
Downs syndrome
Ether
Airway surgeries

13. To prevent or reverse bradycardia
Scoline ‘
Fentanyl
High spinal
Neostigmine
Beta blockade
Surgical stimuli – ECT, sphincter stretching
Gut traction , oculocardiac reflex

14. Low doses and brady ?
Initial brady why ? blocking of muscarinic M2 receptors on the post ganglionic parasympathetic neurons, transiently increasing the amount of acetylcholine in the synapse
Usually complete vagal block needs 3 mg of atropine
Tachycardia more marked in children than elderly
Increase AV conduction
Dilation of vessels of face and a rash
Usually BP unchanged – unless brady - depression

15. Be specific

16. CNS Stimulates medulla stimulates respiratory centre
Auditory hyperacusis
Restlessness
Delirium- later sedation with atropine
Short term memory loss – anesthesia useful ?
Scopolamine – sedation more
Motion sickness – scopolamine
Benzatropine – parkinsons

17. RS and glands
Sweat bronchial and salivary secretions are stopped – dry mouth
Bronchial relaxation
Ipratropium yes – tiotropium is long acting

18. Paralysis of sphincter of iris
Dilation of pupil – homatropine drops
Loss of accommodation more with local atropine than with parenteral

19. Peptic Ulcer •Decrease gastric acid secretion •Selective M1 blocker, Pirenzepine,Telenzepine
Decreased pancreatic secretions
gut spasm,IBS
Travellers diarhoea
Anti emetic effect
LES relax - ? Aspiration risk

20. Atropine fever in children
Atropine bladder
Precipitation of BPH in elderly

21. In OPC poisoning
The recommended starting dose of atropine is 2 mg IV bolus.
Subsequent doses of 2-5mg every 5-15 minutes should be for adequate atropinization
increased heart rate (>100 beats/min.), moderately dilated pupils,
a reduction in bowel sounds, a dry mouth (axillae) and a decrease in bronchial secretions.

22. In OPC poisoning Shots of atropine every 5 minutes
Atropinised in one hour
Then every hour he/ she may need % of the dose received in the first hour as one hour infusion
Inbetween atropinisation lost– one more bolus and increase the infusion rate by 10 %
CNS features – no Glycopyrollate

23. Pharmacokinetics
Atropine is readily absorbed from gut and conjunctival membranes.
Scopolamine is absorbed across the skin, (Transdermal route).
Partially metabolised by the liver.
Eliminated primarily in the urine.
Half life of about 4 hours.
IV and IM routes – OK

24. Doses Atropine glycopyrollate IV dose (mic./Kg) 10-20 5 -10 onset
1 minute
Duration
3 hours
6 hours
Tachycardia
++++ ++
antisialogogue
+++
CNS side effects
CACS +
---
Antiemetic
----
Pupil size --

25. Scopolamine Scopolia cariolica
Sedative, ( DIFFERENCE BETWEEN ATROPINE)
amnesia and antiemetic with antisialogogue
Less tachycardia
What more we want as a premedicant !!
0.3 mg to 0.6 mg IV /IM

26. Poison Hot as a hare: increased body temperature
Blind as a bat: mydriasis (dilated pupils)
Dry as a bone: dry mouth, dry eyes, decreased sweat
Red as a beet: flushed face
Mad as a hatter: delirium

27. ABCDs – pneumonic
Anorexia Blurred vision Constipation/Confusion Dry Mouth Sedation/Stasis of urine

28. Why 0.6 mg atropine One grain = 60 mg 0.6 mg – 1/ 100 grain
Hence ampoules were prepared like that

29. Summary What is it Classification Dose Difference Indication Uses Eyes
Salivary
Gut
Pancreas
Bladder
Bronchus
Sweat
Skin

30. Carry home message !!
Don’t sleep