1. ANTICHOLINERGIC DRUGS
Profs. Abdulqader Alhaider and Hanan Hagar
Pharmacology Department

2. Anticholinergic drugs
What students should know:
Student should be able to :
Describe Kinetics of muscarinic antagonists
The effects of atropine on the major organ systems.
To list the clinical uses of muscarinic antagonists.
To know adverse effects & contraindications of anticholinergic
drugs.
To identify at least one antimuscarinic agent for each of the
following special uses:mydriasis, cyclopedia, peptic ulcer &
parkinsonism.

3. Anticholinergic drugs
are drugs that block cholinergic receptors. Two types are available
1. Nicotinic blockers (antinicotinics).
Ganglionic blockers (not used Clinically Why?)
Neuromuscular blockers (Skeletal Muscle Relaxants)
2. Muscarinic blockers (antimuscarinics)
Naturally occurring alkaloids (e.g: Atropine)
Synthetic atropine substitutes.

4. Anticholinergic drugs
Antimuscarinics
(Parasympatholytics)
Antinicotinics
Ganglionic
blockers
Neuromuscular blockers
Naturally occurring alkaloids
synthetic atropine substitutes

5. Muscarinic antagonists
Natural alkaloids
History (Thousants of years)
Atropine (Hyoscyamine)
Hyoscine (scopolamine)
Esters of tropic acid and tertiary amines
Lipid soluble
Good oral absorption
Good distribution
Cross blood brain barrier (have CNS actions)

6. Muscarinic antagonists
Synthetic atropine substitutes
Tertiary amines
Lipid soluble
central actions
Benztropine
Homatropine
Tropicamaide
Pirenzepine
Oxybutynin
Quaternary amines
Polar, water soluble
No CNS effects
Ipratropium
Glycopyrrolate N+

7. Muscarinic antagonists
Quaternary amines

8. Antimuscarinic drugs Pharmacokinetics DRUG Natural alkaloids
Tertiary amines, lipid soluble, well absorbed, well distributed, good penetration to CNS
Natural alkaloids
Atropine (Hyosyamine)
Hyoscine (scopolamine)
Synthetic atropine substitutes
Tertiary amine
Benztropine
Tertiary amines
Tropicamide
Homatropine
Quaternary amines, not absorbed well, poor distribution, no CNS effects
Ipratropium
Pirenzepine
Quaternary amines
Glycopyrrolate
Oxyphenonium
Oxybutinin

9. Antimuscarinic drugs Mechanism of action
Reversible competitive blockade of muscarinic receptors.
Can antimuscarinic drugs reverse the action of Ach on skeletal muscles?

10. Pharmacological Effects of Antimuscarinic Drugs
CNS
CNS depression
Antiemetic effect (block vomiting center)
antiparkinsonian effect (block ACH at basal ganglia).
Toxic dose:
Hyperthermia - excitement-hallucination.

11. Tachycardia (increase heart rate)
Cardiovascular system (CVS)
Tachycardia (increase heart rate)
AV conduction ( + ve dromotropic effect)
Therapeutic dose:  Vasodilatation induced by cholinomimetics.
Toxic dose: Cutaneous vasodilatation  (atropine flush).
Respiratory system
Bronchial Relaxation (bronchodilator)
 Bronchial secretion   viscosity

12. Eye
Passive mydriasis
due to paralysis of circular muscle
Cycloplegia (loss of near accommodation)
due to paralysis of ciliary muscle.
Loss of light reflex.
Increase I.O.P (worsens glaucoma).
 Lacrimal secretion  sandy eye

13. Salivary secretion  ( Dry mouth ).
Secretions
Salivary secretion  ( Dry mouth ).
 Sweating  Dry skin  Fever in infants and children.
 Bronchial secretion   Viscosity
Lacrimal secretion  Sandy eye 13

14. GIT
Relaxation of smooth muscles.
 GIT motility  Antispasmodic effect.
 Sphincter contractions
Constipation
Urinary Tract
Relaxation of smooth muscles of ureters.
Sphincter contraction.
Urinary retention (worsens prostate hypertrophy).

15. Hyoscine (SCOPOLAMINE)
What is difference between atropine and hyoscine?
Hyoscine has
Shorter duration of action
More CNS depressant action
Antiemetics action in motion sickness
Amnesic action.
Less CVS effect
Can you put a question for exam? 15

16. Anticholinergic actions
Mydriasis
Cycloplegia
relaxation of ciliary muscles
Eye
1. Contraction of circular muscle of iris (miosis)
2. Contraction of ciliary muscles for near vision
Tachycardia ( heart rate)
Heart
bradycardia ( heart rate )
Relaxation of muscles
contraction of sphincter
Urinary bladder
Contraction of muscles
Relaxation of sphincter

17. Anticholinergic drugs
Decrease all secretion
Exocrine glands
Increase of sweat, saliva, lacrimal, bronchial, intestinal secretions
peristalsis
secretion
Contraction of sphincter
GIT
relaxation of sphincter
1. Bronchodilatation
2. Decrease secretion
Lung
Bronchoconstriction
bronchial secretion

18. Uses of antimuscarinic drugs
organ
Drugs
Cardiac Arrest How?
Rx of pesticide Toxicity
CNS
Atropine
Preanesthetic medication,
Motion sickness, antispasmodic
Hyoscine
Parkinson's disease
Benztropine
Fundus examination of eye
Eye
Tropicamide
Homatropine
asthma, COPD, inhalation
Respiratory system
Ipratropium
Peptic ulcer
Stomach
Pirenzepine
Antispasmodics in hypermotility
GIT
Glycopyyrolate
Propantheline
Urinary urgency, Urinary incontinence
GUT
Oxybutynin

19. Antidote: Physostigmine ( IV slowly).
Adverse effects (usually can be observed with antidepressant s and antipsychotics)
Eye: Blurred vision – Mydriasis
CVS: Tachycardia - Atropine flush
GUT: Urinary retention
GIT: Constipation, paralytic ileus
Secretions: Dryness of mouth , Sandy eye
Increased body temperature.
CNS: sedation, hallucination, excitation (Toxic dose).
Treatment
Gastric lavage.
Anticonvulsant.
Cooling blanket.
Antidote: Physostigmine ( IV slowly).

20. Treatment of anticholinergic Toxicities
Gastric lavage.
Anticonvulsant.
Cooling blanket.
Antidote: Physostigmine ( IV slowly).

21. Contraindications Glaucoma (angle closure glaucoma) Tachycardia
Prostate hypertrophy in old patients.
Constipation, paralytic ileus, intestinal obstruction.
Children in case of atropine

22. Thank you Questions ?