This document summarizes anticholinergic/antimuscarinic drugs. It discusses their pharmacological actions, classifications, examples like atropine, and therapeutic uses. Atropine is obtained from belladonna plants and acts as a muscarinic receptor antagonist. It has effects in the CNS, CVS, eyes, smooth muscles and exocrine glands. Atropine is used to treat conditions like peptic ulcer, intestinal spasms, asthma, Parkinson's disease, motion sickness and as a antidote for poisoning. Ganglionic stimulants and blockers are also discussed.

1. Dr. Ravi Mundugaru
Assistant Professor
Dept. of Pharmacology
ADICHUNCHANGIRI INSTITUTE OF MEDICAL SCINCES, B.G. Nagar
Anti Cholinergic Drugs/
Antimuscarinic drugs

2. Pharmacological action Acetyl
choline

3.  Muscarinic receptor antagonist/ Atropine
 Parasympatholytics
Muscarinic receptor antagonists
Conventionally – Blocks actions of Ach on
autonomic effectors and in CNS exerted through
muscarinic receptors.
 Nicotinic Receptor blockers Ganglion
blockers
Neuromuscluar

4. CLASSIFICATION
1. Natural Alkaloids
 Atropine
 Hyoscine (Scopolamine)
2. Semi Synthetic derivatives
 Homatropine
 Atropine Methonitrate
 Hyoscine butyl bromide
 Ipratropium bromide
 Tiotropium bromide.

5. 3. Synthetic Compounds
a) Mydriatics : Cyclopentolate, Tropicamide
b) Anti Secretory – Anti spasmodics :
- Quarternary compounds – Propantheline, Oxyphenonium,
Glycopyrrolate, Clindinium
- Tertiary amines : Dicyclomine, Pirenzapine.
c) Vesicoselective: Oxybutynin, Flavoxate, Toltirodine
c) Anti parkinsonian :Trihexyphenidyl (Benzhexol)
Procyclidine, Biperidine
4. Others : Tricyclic antidepressants, Phenothiazines, Anti
histaminics

6. ATROPINE
 Obtained from plant Atropa belladona.
 Atropine & hyoscine (scopalamine) are belladone
alkaloids.
 Same actions except – Atropine is CNS stimulant &
hyoscine is CNS depressant.
 Blocks Muscarinic Receptors & Prevents action of Ach
on these receptors
 Muscarinic Blocker.

7. Pharmacological actions
CNS
 Atropine is a CNS stimulant at high dose
 Hyoscine is CNS depressant even at low doses.
 Stimulate many medullary centers – Vagal, Resp, Vasomotor
 Blocks cholinergic overactivity is basal ganglia & supress
tremors and rigidity of parkinsonism.
 High doses – Cortical excitation, Restlesness, disorientation,
hallucination, delirium – Resp depression, Coma
 Depress Vestibular Excitation & has anti-motion sickness
property (because of cholinergic link in vestibular pathway)

8. CVS
 ↑ HR because of M2 receptors on SA Node through
which vagal tone ↓ H.R (tone more in young adults)
 Has vasodilator action at high dose & lowers B.P (also
because of histamine release)
EYES
Mydriasis, abolish light reflex, Cycloplegia 7-10 days,
photo phobia, blurring of vision, ↑ IOT, Glaucoma
(narrow angle)

11.  SMOOTH MUSCLES (M3 blockade)
G.I.T – tone, amplitude of contraction of stomach and intestine are
reduced → ↓peristalsis → relieves spasm
Biliary tract : Sm muscles relaxed → Biliary spasm relieved
Bronchi: Bronchodilatation → ↓airway resistance.(asthma & COPD)
Genito urinary tract : Relaxant effect on ureter & urinary bladder
Urinary retention (used esp in elderly with prostatic hypertrophy)
 Exocrine GLANDS
Reduces all secretions except milk.
Lacrimation ------------- Dry eyes
Salivary ------------------ difficulty in
Nasopharyngeal -------- swallowing ↓ Reduced
Tracheobronchial
Sweat -------------------- Dry skin ↑ temp.

12.  Gastric secretion ↓ Volume & quantity of acid pepsin &
mucous in stomach.
 Intestinal & pancreatic secretions not significantly reduced.
 BODY TEMPERATURE
↑ At high doses because of ↓sweating
Stimulation of temp regulating
center in hypothalamus
 LOCALANAESTHETIC
Mild on cornea

13.  PHARMACO KINETICS
o Well absorbed orally
o Crosses BBB (Atropine 50%, Hyocine easily cross
BBB)
o Partly Metabolized in liver, T ½ 3-4 hours.
o Excreted in Urine

14. ADVERSE EFFECTS
o Common but not serious
o Blurring of vision
o Dryness of mouth
o Difficulty in swallowing & speech
o Fever
o Constipation
o Urinary retention
o Skin rashes, flushing
o Restlesness, hallucinations , delerium
o Convulsions & coma
o Poisoning treated with physostigmine I.V

15. Rx → Atropine poisoning
 If ingested, gastric lavage with tannic acid (KmNO4 not effective
in oxidizing31 atropine)
 Patient kept in dark & quiet room.
 Cold sponging / ice bags.
 Physostigmine 1-3mg S.C/I.V repeated every 4-6 min.
 Maintain BP.
 Artificial respiration.
 Diazepam IV to control convulsions.
C/I – Individuals with narrow iridocorneal angle – may
precipitate Acute Congestive glaucoma
-- Elderly male with prostatic hypertrophy.

16. Drug interactions
 Slow absorption of other drugs Eg: Levodopa
 Antacids interferes with absorption of anticholinergics.
 Anti-histamines
Tri cyclic antidepressants Have anticholinergic property
Phenothiazines additive effects
 MAO inhibitors interfere with anticholinergic antiparkinsonian
drugs – delirium.

17. Therapeutic uses
 As Antisecretory
1. Pre anaesthetic medication
Irritant G.A ↑ secretion Bronchospasm
(Ether) Laryngospasm
- Atropine, Hyoscine, Glycopyrrolate.
2. Peptic ulcer
- Effective dose – side effect
- Pirenzapine H2 blocker preferred.

18.  As Antispasmodic
1. Intestinal, renal colic, biliary colic
(Nitrate or atropine+morphine preferred)
2. Diarrhoea Nervous
Functional Atropine +
Drug induced Diphenoxylate
Travellers (Lomotil)
3. Pylorospasm, Gastric hyper motility
4. To relieve urinary frequency & urgency & nocturnal enuresis
in children – Oxybutinin, Flavoxate – effective.
5. Dysmenorrhea : Not very effective.

19.  Bronchial Asthma, COPD, Chr. Bronchitis
Reflex vagal activity → Bronchospasm & ↑ secretion
in COPD & Chr bronchitis
Atropine → dried up secretions – plugging
of bronchioles
Ipratropium bromide → aerosol route → broncho dilation
without decreasing secretions with
minimal side effects.

20. As Mydriatic & Cycloplegic
Refractive error measurement
Tropicamide replaced homatropine /
cyclopentolate
Fundoscopy, retinoscopy – phenylephrine
Iritis, iridocyclitis, keratitis
Alternate with miotic → prevent adhesion &
break if already formed.

21.  As Cardiac Vagolytic
Marked reflex vagal discharge – pain of M.I
↓
Bradycardia, heart block.
Atropine is useful in preventing bradycardia.

22. As a Antiparkinson :
Tremor & rigidity → relative excess of cholinergic
activity because of deficiency of dopaminergic
activity in the basal ganglia – striatum system.
Combination of anti cholinergic with a dopamine
precursor provide more effective therapy than
either drug alone.
- drug induced extrapyramidal symptoms.

23. 2. Motion sickness
Scopolamine IM/Mouth/Transdermal patch
Useful dose → sedation, dry mouth. 48-72 hours.
Hyoscine is used to produce sedation & amnesia during labour.
 To antagonise muscarinic effects of drugs & poisons.
Antidote for Anticholinesterase poisoning
Mushroom poisoning
Used to block muscarinic effect of neostigmine when used for
- Myasthenia gravis
- decurarisation
- Cobra envenomation.

24. Ganglionic Stimulants
Selective Nicotinic Agonist Non selective nicotinic agonist
Nicotine Acetyl choline
Lobeline Carbachol
Dimethyl phenyl piperazinium
(DMPP)
Pilocarpine
Tetramethyl ammonium
Varenicline
Anti cholinesterase
Nicotine
From : Nicotiana tobaccum
Nicotine transdermal patch → an aid to smoking
cessation.
NICOTINELL-TTS, 10, 20, 30 cm2 → 7, 14, 21 mg / 24
hours.

25. Ganglion Blocking Agents
1. Competitive blockers
a. Quaternary ammonium compounds
Hexamethonium, pentolinium
b. Amines
Mecamylamine, pempidine
c. Monosulfonium compound
Trimmethaphan camforsulfonate
2. Persistant depolarising blockers
Nicotine (Large dose)
Anticholinesterases (Large dose)
ADR EFFECTS : Tachycardia, Postural + exercise hypotension,
constipation, difficulty in micturition, dry mouth, photophobia.