1. Cholinergic antagonists

2. Anti- muscarinic agents
sites of action
1. Secretions by salivary, bronchial and sweat glands.
2. The eye and cardiac responses mediated by the vagus.
3. Urinary bladder and GI tract.
4. Gastric secretions.

3. Naturally occurring
Atropine ( belladonna )
Scopolamine
Homatropine

4. ATROPINE – high affinity for muscarinic receptors
ATROPINE – high affinity for muscarinic receptors. acts both centrally and peripherally.
Mydriasis, cycloplegia.
Eneuresis in children
Low doses- bradycardia.
High doses—tachycardia
Dilates cutaneous vasculature

5. Atropine uses
In ophthalmology –mydriatic/ cycloplegic
Spastic disorders of GI and lower urinary tract.
To treat OP poisoning
To suppress respiratory secretions prior to surgery.

6. Synthetic quaternary ammonium antimuscarinic agents.
Ipratropium
Propantheline

7. Synthetic tertiary amine muscarinic antagonists
Cyclopentolate
Tropicamide
Dicyclomine
Pirenzipine

8. CNS
Due to its greater lipid solubility, scopolamine has significant CNS effects even at low therapeutic doses.
An adjunct for anesthesia due to an ability to decrease short term memory.
Motion sickness (scopolamine)
Antipsychotic therapy: used to treat the extrapyramidal symptoms

9. Eye Mydriasis Refract the eye during ophthalmic examinations.
Caution : glaucoma

10. Heart
Low doses initially produce bradycardia, but later doses produce tachycardia.
Some times in Surgery/catheterization

11. Lung Broncho -dilation: Ipratropium
Mainly used as inhalation in treating asthma and COPD.
Atropine prior to surgery will decrease the respiratory secretions

12. GI tract Salivary secretions decrease
Can cause dry mouth and difficulty in swallowing
Only Pirenzepine has some potency to decrease hyperacidity..

13. Other uses With an opioid to relax the ureter in renal colic.
To increase the capacity and decrease the frequency of bladder contractions, i.e.enuresis in children.
To decrease the frequency of urination in spastic paraplegia.

14. Toxic effects decreased concentration and memory drowsiness sedation
excitation
ataxia
asynergia
disorientation
hallucinations
coma

15. ATROPINE PSYCHOSIS
Disorientation, confusion, recent loss of memory, agitation, incoherent speech, restlessness, hallucinations, anxiety and delirium.
Treatment – symptomatic only and discontinue the drug immediately.

16. Therapeutic uses of muscarinic antagonists
1. Premedication
· Atropine
· Given before operations to prevent unwanted M stimulation.
· Want to eliminate bronchial secretions (don't want the patient to choke on their own secretions)
· Want to block vagal stimulation to the heart and lungs (want to keep airways open)
· During induction of anesthesia, there may be excessive vagal stimulation, which we want to eliminate.

17. Anticholinesterase toxicity
Toxicity due to over dose of physostigmine and other anticholinesterases
Atropine is used to treat this condition by blocking all M receptors.

18. 2. Antispasmodic
· Hyoscine N butyl Bromide
· A quaternary derivative
· Treats colic
3. Bronchodilator (asthma)
· Ipratropium
· Given by inhalation, get a local effect

19. Homatropine
· Much shorter action than atropine
· It is the drug of choice when doing investigations of the eye, since it dilates the pupil for a short time only.

20. 4.Treatment of peptic ulcers
· Pirenzepine
· Selective M1 antagonist
· Not as good as H2 antagonists (e.g. cimetidine) or proton pump inhibitors (e.g. omeprazole)

21. 5. Parkinson's disease
· Benztropine, trihexiphenidyl
also used to treat the extrapyramidal symptoms due to Antipsychotic drugs
6. Motion sickness
· Hyoscine, scopolamine

22. REMEMBER
S --- salivation
L --- lacrimation
U --- urination
D --- diaphoresis
G --- GI
E --- Eye & emesis

23. GANGLIONIC BLOCKERS
NICOTINE
TRIMETHAPHAN
MECAMYLAMINE

24. SITE OF ACTION ALL NICOTINIC RECEPTORS IN ANS ( BOTH SNS AND PNS )
IN CNS

25. NICOTINE
DOSAGE
LOW DOSE
HIGH DOSE
GANGLION
STIMULATION
BLOCK

26. CNS/ NICOTINE LOW DOSE- EUPHORIA,RELAXATION HIGH DOSE-
central respiratory paralysis
hypotension- medullary paralysis

27. PERIPHERAL EFFECTS
COMPLEX
HR RAISES
B.P.- RAISES
GIT- MOTILITY RAISES

28. OTHERS
TRIMETHAPHAN- SHORT ACTING
HTN EMERGENCIES
used in surgery, particularly neurosurgery, to produce a relatively bloodless operative field (controlled hypotension).

29. MECAMYLAMINE- LONG ACTING
CHR. CASES of HTN

30. Neuromuscular Blocking Drugs
Mainly during surgery to produce complete muscle relaxation, without giving higher anesthetic doses.

31. Neuro muscular blocking drugs
Atracurium
Doxacurium
Mivacurium
Pancuronium
Rocuronium
Succinylcholine
Tubocurarine
Vecuronium

32. Atracurium
safe in renal failure, used in critically ill patients for mechanical ventilation.
Short duration of action – so suitable for short surgical procedures.

33. Rocuronium & Succinylcholine
Rapid onset of action – so used mainly in tracheal intubation in patients with gastric contents.
Vecuronium – short duration of action , so used in short surgical procedures.

34. Imp side effects
Tubocurarine – induce histamine release and also lower B.P.
Pancuronium – Increased H.R.
Succinylcholine – malignant hyperthermia, hyperkalemia and increased Intraocular pressure.