Anticholinergics (VK)

1. AnticholinergicsAnticholinergics

2. AnticholinergicsAnticholinergics
Drugs that block or inhibit the actions of Drugs that block or inhibit the actions of
acetylcholine (ACh) in the parasympathetic nervous acetylcholine (ACh) in the parasympathetic nervous
system (PSNS) i.e. on muscarinic receptors: system (PSNS) i.e. on muscarinic receptors:
Autonomic effectors Autonomic effectors
CNSCNS
Nicotinic antagonists also block certain actions of Nicotinic antagonists also block certain actions of
Ach, they are generally referred to as- Ganglionic Ach, they are generally referred to as- Ganglionic
blockers / NMBsblockers / NMBs

3. Cholinergic Blocking Agents: Cholinergic Blocking Agents:
Mechanism of ActionMechanism of Action
Competitive antagonistsCompetitive antagonists
Compete with AChCompete with ACh
Block ACh at the muscarinic receptors Block ACh at the muscarinic receptors
in the PSNSin the PSNS
As a result, ACh is unable to bind to theAs a result, ACh is unable to bind to the
receptor site and cause a cholinergic effect.receptor site and cause a cholinergic effect.

4. ClassificationClassification
Natural:Natural: Atropine, Atropine,
Hyoscine (Scopolamine)Hyoscine (Scopolamine)
SemisyntheticSemisynthetic::HomatropineHomatropine
Atropine methonitrateAtropine methonitrate
Ipratropium bromideIpratropium bromide
Hyoscine butylbromideHyoscine butylbromide

5. Synthetic:Synthetic:
a)a)MydriaticsMydriatics:: Cyclopentonate, Tropicamide Cyclopentonate, Tropicamide
b) Antisecretory antispasmodic:b) Antisecretory antispasmodic:
I) Quaternary compounds:I) Quaternary compounds:
Propantheline, Clidinium, Oxyphenonium,Propantheline, Clidinium, Oxyphenonium,
Pipenzolate methyl bromide, Glycopyrolate.Pipenzolate methyl bromide, Glycopyrolate.
II) Tertiary compoundsII) Tertiary compounds:: Dicyclomine, Pirenzepine Dicyclomine, Pirenzepine
c) Vasicoselectivec) Vasicoselective:: Oxybutinin, Flavoxate, Tolterodine Oxybutinin, Flavoxate, Tolterodine
d) Antiparkinsoniand) Antiparkinsonian:: Trihexyphenidyl, Biperidin. Trihexyphenidyl, Biperidin.

6. Pharmacological actionsPharmacological actions
Atropine as prototypeAtropine as prototype
CNSCNS
Overall CNS stimulant effectOverall CNS stimulant effect
Small doses: These effects are not appericiable,Small doses: These effects are not appericiable,
decrease muscle rigidity and tremorsdecrease muscle rigidity and tremors
Large doses: stimulates medullary centres- vagal , Large doses: stimulates medullary centres- vagal ,
respiratory, vasomotor centres respiratory, vasomotor centres
drowsiness, disorientation, hallucinations –(cortical drowsiness, disorientation, hallucinations –(cortical
excitation)excitation)
Depresses vestibular excitation- antimotion sickness Depresses vestibular excitation- antimotion sickness
property.property.

7. CardiovascularCardiovascular
Small doses: decrease heart rate Small doses: decrease heart rate
Large doses: increase heart rate, facilitates AV Large doses: increase heart rate, facilitates AV
conduction.conduction.
No considerable effect on BPNo considerable effect on BP
EyeEye
Dilated pupils (mydriasis)Dilated pupils (mydriasis)
Decreased accommodation due to paralysis Decreased accommodation due to paralysis
of ciliary muscles (cycloplegia lasting for 7-10 days)of ciliary muscles (cycloplegia lasting for 7-10 days)
This results into long lasting blurring of vision and This results into long lasting blurring of vision and
photophobiaphotophobia
Body temperatureBody temperature
Rise in body temp.high dosesRise in body temp.high doses
Local anaestheticLocal anaesthetic

8. GastrointestinalGastrointestinal
Relax smooth muscle tone of GI tractRelax smooth muscle tone of GI tract
Decrease intestinal and gastric secretionsDecrease intestinal and gastric secretions
Decrease motility and peristalsis Decrease motility and peristalsis
GenitourinaryGenitourinary
Relaxed detrusor muscleRelaxed detrusor muscle
Increased constriction of internal sphincterIncreased constriction of internal sphincter
Result: urinary retentionResult: urinary retention
GlandularGlandular
Decreased bronchial secretions, salivation, sweatingDecreased bronchial secretions, salivation, sweating
RespiratoryRespiratory
Decreased bronchial secretionsDecreased bronchial secretions
Dilated bronchial airwaysDilated bronchial airways

9. Atropine substitutesAtropine substitutes
Quaternary compoundsQuaternary compounds
Hyoscine butyl bromide-Hyoscine butyl bromide- 20-40mg oral, i.m., 20-40mg oral, i.m.,
Use- oesophageal, Gi spastic conditions.Use- oesophageal, Gi spastic conditions.
Atropine methonitrateAtropine methonitrate-2.5-10mg orally, im-2.5-10mg orally, im
Use-abdominal colic, hyperacidityUse-abdominal colic, hyperacidity
Ipratropium bromideIpratropium bromide-40-80microgram inhalational-40-80microgram inhalational
Use-COPD, Bronchial asthmaUse-COPD, Bronchial asthma

10. Quaternary compoundsQuaternary compounds
GlycopyrrolateGlycopyrrolate: 0.1-0.3 mg im,1-2 mg oral: 0.1-0.3 mg im,1-2 mg oral
No central effectNo central effect
Potent and rapidly acting antimuscarinicPotent and rapidly acting antimuscarinic
Use- For preanaesthetic medication and during Use- For preanaesthetic medication and during
anaesthesia anaesthesia
Propanthelin, Clidinium, Oxyphenonium-Propanthelin, Clidinium, Oxyphenonium-
Use- peptic ulcer , gastritis, irritable bowel Use- peptic ulcer , gastritis, irritable bowel
syndrome, colic, gi hypermotility syndrome, colic, gi hypermotility

11. Tertiary aminesTertiary amines
Dicyclomine Dicyclomine :20mg oral/im:20mg oral/im
Direct smooth muscle relaxant actionDirect smooth muscle relaxant action
Antispasmodic actionAntispasmodic action
AntiemeticAntiemetic
Use: Dysmenorrhea, irritable bowel syndrome, Use: Dysmenorrhea, irritable bowel syndrome,
motion sickness, morning sickness. motion sickness, morning sickness.
Pirenzepine :Use-relief of peptic ulcer painPirenzepine :Use-relief of peptic ulcer pain

12. Vasicoselective drugsVasicoselective drugs
OxybutininOxybutinin
High affinity for receptors of urinary bladder, and High affinity for receptors of urinary bladder, and
salivary glandssalivary glands
Uses : Uses : Neurogenic bladderNeurogenic bladder
spina bifidaspina bifida
nocturnal enuresisnocturnal enuresis
overactive bladder-urinary urgency, overactive bladder-urinary urgency,
frequency, dysuriafrequency, dysuria

13. MydriaticsMydriatics
AtropineAtropine
PotentPotent
Slow & Longer actingSlow & Longer acting
Undesirable for refraction tesingUndesirable for refraction tesing
Pupils dilates in 30-40mins,cycloplegia in 1-3 hrs last for a weekPupils dilates in 30-40mins,cycloplegia in 1-3 hrs last for a week
HomatropineHomatropine
10 times less potent than atropine10 times less potent than atropine
Dilatation takes 45-60mins last for 1-3 daysDilatation takes 45-60mins last for 1-3 days
CyclopentonateCyclopentonate
Potent and fast acting (dilatation 30-60mins and last for 1day)Potent and fast acting (dilatation 30-60mins and last for 1day)
Preffered for cycloplegic refraction, uveitis, iritisPreffered for cycloplegic refraction, uveitis, iritis
Adverse effects-transient behavioral abnormalitiesAdverse effects-transient behavioral abnormalities
Tropicamide Tropicamide
Quickest (onset-20-40mins , brief duration for 3-6 hrs)Quickest (onset-20-40mins , brief duration for 3-6 hrs)
Satisfactory for refraction testing in adults and for fundoscopySatisfactory for refraction testing in adults and for fundoscopy

14. UsesUses
As antisecretoryAs antisecretory
Preanaesthetic medication-(Atropine, glycopyrolate, hyosine)Preanaesthetic medication-(Atropine, glycopyrolate, hyosine)
Peptic ulcersPeptic ulcers
Pulmonary embolismPulmonary embolism
To check sweating , salivation in parkinsonismTo check sweating , salivation in parkinsonism
As antispasmodicAs antispasmodic
Intestinal, biliary, renal colic, abdominal crampsIntestinal, biliary, renal colic, abdominal cramps
Nervous , functional diarrheoaNervous , functional diarrheoa
Irritable bowel syndrome, spastic constpationIrritable bowel syndrome, spastic constpation
Pylorospasm, gastric hypermotility, gastritis, gastric dyspepsiaPylorospasm, gastric hypermotility, gastritis, gastric dyspepsia
Urinary frequency, urgency, enuresis in childrenUrinary frequency, urgency, enuresis in children
dysmenorrheadysmenorrhea

15. Bronchial asthma, COPDBronchial asthma, COPD
As mydriatic and cycloplegicAs mydriatic and cycloplegic
Diagnostic Diagnostic
therapeutictherapeutic
As cardiac vagolyticAs cardiac vagolytic
In partial AV blockIn partial AV block
AMI, digitalis toxicityAMI, digitalis toxicity
For central actionFor central action
Motion sicknessMotion sickness
AntiparkinsonianAntiparkinsonian
OPPsOPPs

16. Cholinergic Blocking Agents: Cholinergic Blocking Agents:
Therapeutic UsesTherapeutic Uses
CNSCNS
Decreased muscle rigidity and muscle tremorsDecreased muscle rigidity and muscle tremors
Parkinson’s diseaseParkinson’s disease
Drug-induced extrapyramidal reactionsDrug-induced extrapyramidal reactions

17. Cholinergic Blocking Agents: Cholinergic Blocking Agents:
Therapeutic UsesTherapeutic Uses
CardiovascularCardiovascular
Affect the heart’s conduction systemAffect the heart’s conduction system
Low doses: slow the heart rateLow doses: slow the heart rate
High doses: block inhibitory vagal effects on High doses: block inhibitory vagal effects on
the SA and AV node pacemaker cellsthe SA and AV node pacemaker cells
Result: increased heart rateResult: increased heart rate

18. Cholinergic Blocking Agents: Cholinergic Blocking Agents:
Therapeutic UsesTherapeutic Uses
AtropineAtropine
Used primarily for cardiovascular disordersUsed primarily for cardiovascular disorders
Sinus node dysfunctionSinus node dysfunction
Symptomatic second-degree heart blockSymptomatic second-degree heart block
Sinus bradycardia with hemodynamic compromise Sinus bradycardia with hemodynamic compromise
(advanced life support)(advanced life support)

19. Cholinergic Blocking Agents: Cholinergic Blocking Agents:
Therapeutic Uses Therapeutic Uses
RespiratoryRespiratory
Blocking the cholinergic stimulation of the PSNS Blocking the cholinergic stimulation of the PSNS
allows unopposed action of the SNS.allows unopposed action of the SNS.
Results:Results:
Decreased secretions from nose, mouth, Decreased secretions from nose, mouth,
pharynx, bronchipharynx, bronchi
Relaxed smooth muscles in bronchi Relaxed smooth muscles in bronchi
and bronchiolesand bronchioles
Decreased airway resistanceDecreased airway resistance
BronchodilationBronchodilation

20. Cholinergic Blocking Agents: Cholinergic Blocking Agents:
Therapeutic UsesTherapeutic Uses
Respiratory agents are used to treat:Respiratory agents are used to treat:
Exercise-induced bronchospasmsExercise-induced bronchospasms
Chronic bronchitisChronic bronchitis
AsthmaAsthma
Chronic obstructive pulmonary diseaseChronic obstructive pulmonary disease

21. Cholinergic Blocking Agents: Cholinergic Blocking Agents:
Therapeutic Uses Therapeutic Uses
GastrointestinalGastrointestinal
PSNS controls gastric secretions and smooth PSNS controls gastric secretions and smooth
muscles that produce gastric motility.muscles that produce gastric motility.
Blockade of PSNS results in:Blockade of PSNS results in:
Decreased secretionsDecreased secretions
Relaxation of smooth muscleRelaxation of smooth muscle
Decreased GI motility and peristalsisDecreased GI motility and peristalsis

22. Cholinergic Blocking Agents: Cholinergic Blocking Agents:
Therapeutic UsesTherapeutic Uses
Gastrointestinal agents are used to treat:Gastrointestinal agents are used to treat:
Peptic ulcer diseasePeptic ulcer disease
Irritable bowel diseaseIrritable bowel disease
GI hypersecretory statesGI hypersecretory states

23. Cholinergic Blocking Agents: Cholinergic Blocking Agents:
Therapeutic Uses Therapeutic Uses
GenitourinaryGenitourinary
Relaxed detrusor muscles of the bladderRelaxed detrusor muscles of the bladder
Increased constriction of the internal sphincterIncreased constriction of the internal sphincter
Reflex neurogenic bladderReflex neurogenic bladder
Incontinence Incontinence

24. Cholinergic Blocking Agents: Cholinergic Blocking Agents:
Side EffectsSide Effects
Body SystemBody SystemSide/Adverse EffectsSide/Adverse Effects
CardiovascularCardiovascularIncreased heart rate, Increased heart rate,
dysrhythmiasdysrhythmias
CNSCNS CNS excitation, restlessness, CNS excitation, restlessness,
irritability, disorientation, irritability, disorientation,
hallucinations, deliriumhallucinations, delirium

25. Cholinergic Blocking Agents: Cholinergic Blocking Agents:
Side EffectsSide Effects
Body SystemBody System Side/Adverse EffectsSide/Adverse Effects
EyeEye Dilated pupils, decreased Dilated pupils, decreased
visual accommodation, visual accommodation,
increased intraocular pressureincreased intraocular pressure
GastrointestinalGastrointestinalDecreased salivation, Decreased salivation,
decreased gastric secretions, decreased gastric secretions,
decreased motilitydecreased motility

26. Cholinergic Blocking Agents: Cholinergic Blocking Agents:
Side EffectsSide Effects
Body SystemBody System Side/Adverse EffectsSide/Adverse Effects
GenitourinaryGenitourinary Urinary retentionUrinary retention
GlandularGlandular Decreased sweatingDecreased sweating
RespiratoryRespiratory Decreased bronchial secretionsDecreased bronchial secretions