Pharmacology Third Year

1. AnticholinergicAnticholinergic
drugsdrugs
Dr Heba A. Mahmoud

3. Anti-muscarinic drugsAnti-muscarinic drugs
Mode of action:
Competitive antagonist compete with acetyl
choline for muscarinic receptors

4. Actions ofActions of Anti-CholinergicsAnti-CholinergicsActions ofActions of Anti-CholinergicsAnti-Cholinergics
Eye: blocks all cholinergic activity on the eye, resulting in
 passive mydriasis
 cycloplegia (inability to focus for near vision).
 Increase intraocular pressure
CVS: ↑HR (after initial HR)↓
↑ AVN conduction
Large dose atropine flush
Respiratory system: bronchodilatation
↓ secretions

5. Actions of Anti-CholinergicsActions of Anti-Cholinergics
GIT: antispasmodic reduce gastrointestinal tract motility
↓ gastric secretion
dry mouth and constipation
Urinary system: Relax bladder and retention of urine
Secretions: decrease all secretions (except milk, bile)
CNS: excitatory , inhibition of Vomiting centre ,
antiparkinsonian.
Anti-motion sickness

6. Therapeutic uses of Anti-CholinergicsTherapeutic uses of Anti-Cholinergics
Fundus examination and iridocyclitis (Mydriatic )
Atropine
Tropicamide is used but short acting, 2 - 4 hrs
Antidote for cholinergic agonists e.g. Organophosphorus
poisoning (Atropine )
 Heart block, vasovagal attack (Atropine )
Intestinal, biliary and renal Colic (hyoscine butyl
bromide)
Motion sickness (hyoscine)
Peptic ulcer: pirenzepine

7. Therapeutic uses of Anti-CholinergicsTherapeutic uses of Anti-Cholinergics
(cont.)(cont.)
Nocturnal enuresis and urinary incontinence
(emebronium is better) .
Parkinsonism (benztropine)
Bronchial asthma ipratropium is used by inhalation
Preanesthetic medication to stimulate respiratory
center , prevents vomiting, prevent excess
bronchial and salivary secretions and protect heart
from excess vagal tone
(Hyoscine)

8. Anti-CholinergicsAnti-Cholinergics adverse effectsadverse effects
 Dry mouth
 Blurred vision, xero-ophthalmia (dry eye), glaucoma
 Tachycardia
 Constipation
 Retention of urine
 Hot and flushed skin
Anti-CholinergicsAnti-Cholinergics contraindicationcontraindication
 Glaucoma
 Tachycardia
 Paralytic ileus
 Senile hypertrophy of prostate
 Allergy to atropine