anticholinergics (vk)

AnticholinergicAnticholinergicss

AnticholinergicsAnticholinergics Drugs that block or inhibit the actions of Drugs that block or inhibit the actions of

acetylcholine (ACh) in the acetylcholine (ACh) in the parasympathetic nervous system (PSNS) parasympathetic nervous system (PSNS) i.e. on muscarinic receptors: Autonomic i.e. on muscarinic receptors: Autonomic effectors effectors

CNSCNS Nicotinic antagonists also block certain Nicotinic antagonists also block certain

actions of Ach, they are generally referred actions of Ach, they are generally referred to as- Ganglionic blockers / NMBsto as- Ganglionic blockers / NMBs

Cholinergic Blocking Cholinergic Blocking Agents: Mechanism of Agents: Mechanism of

ActionAction Competitive antagonistsCompetitive antagonists Compete with AChCompete with ACh Block ACh at the muscarinic Block ACh at the muscarinic

receptors 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 receptor site and cause a cholinergic effect.effect.

ClassificationClassification

Natural:Natural: Atropine, Atropine, Hyoscine Hyoscine

(Scopolamine)(Scopolamine) SemisyntheticSemisynthetic:: HomatropineHomatropine

Atropine methonitrateAtropine methonitrate

Ipratropium bromideIpratropium bromide

Hyoscine butylbromideHyoscine butylbromide

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, Dicyclomine, PirenzepinePirenzepine

c) Vasicoselectivec) Vasicoselective:: Oxybutinin, Flavoxate, Oxybutinin, Flavoxate, TolterodineTolterodine

d) Antiparkinsoniand) Antiparkinsonian:: Trihexyphenidyl, Trihexyphenidyl, Biperidin.Biperidin.

Pharmacological actionsPharmacological actionsAtropine as prototypeAtropine as prototype

CNSCNS Overall CNS stimulant effectOverall CNS stimulant effect Small doses: These effects are not Small doses: These effects are not

appericiable,appericiable,

decrease muscle rigidity and tremorsdecrease muscle rigidity and tremors Large doses: stimulates medullary centres- Large doses: stimulates medullary centres-

vagal , vagal , respiratory, respiratory, vasomotor centresvasomotor centres

drowsiness, disorientation, hallucinations –(cortical drowsiness, disorientation, hallucinations –(cortical excitation)excitation)

Depresses vestibular excitation- antimotion Depresses vestibular excitation- antimotion sickness property.sickness property.

CardiovascularCardiovascular Small doses: decrease heart rate Small doses: decrease heart rate Large doses: increase heart rate, Large doses: increase heart rate,

facilitates AV conduction.facilitates AV conduction. No considerable effect on BPNo considerable effect on BP

EyeEye Dilated pupils (mydriasis)Dilated pupils (mydriasis) Decreased accommodation due to Decreased accommodation due to

paralysis paralysis of ciliary muscles (cycloplegia lasting for of ciliary muscles (cycloplegia lasting for 7-10 days)7-10 days)

This results into long lasting blurring of This results into long lasting blurring of vision and photophobiavision and photophobia

Body temperatureBody temperature Rise in body temp.high dosesRise in body temp.high doses

Local anaestheticLocal anaesthetic

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, Decreased bronchial secretions, salivation,

sweatingsweating

RespiratoryRespiratory Decreased bronchial secretionsDecreased bronchial secretions

Dilated bronchial airwaysDilated bronchial airways

Atropine substitutesAtropine substitutes

Quaternary compoundsQuaternary compounds Hyoscine butyl bromide-Hyoscine butyl bromide- 20-40mg oral, 20-40mg oral,

i.m.,i.m.,Use- oesophageal, Gi spastic conditions.Use- oesophageal, Gi spastic conditions.

Atropine methonitrateAtropine methonitrate-2.5-10mg orally, im-2.5-10mg orally, imUse-abdominal colic, hyperacidityUse-abdominal colic, hyperacidity

Ipratropium bromideIpratropium bromide-40-80microgram -40-80microgram inhalationalinhalationalUse-COPD, Bronchial asthmaUse-COPD, Bronchial asthma

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 Use- For preanaesthetic medication and

during during anaesthesia anaesthesia

Propanthelin, Clidinium, Oxyphenonium-Propanthelin, Clidinium, Oxyphenonium-Use- peptic ulcer , gastritis, irritable Use- peptic ulcer , gastritis, irritable bowel syndrome, colic, gi hypermotility bowel syndrome, colic, gi hypermotility

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 Use: Dysmenorrhea, irritable bowel

syndrome, syndrome, motion motion sickness, morning sickness.sickness, morning sickness.

Pirenzepine :Use-relief of peptic Pirenzepine :Use-relief of peptic ulcer painulcer pain

Vasicoselective drugsVasicoselective drugs

OxybutininOxybutinin High affinity for receptors of urinary High affinity for receptors of urinary

bladder, and salivary glandsbladder, and salivary glands Uses : Uses : Neurogenic bladderNeurogenic bladder

spina bifidaspina bifida

nocturnal enuresisnocturnal enuresis

overactive bladder-urinary overactive bladder-urinary urgency, urgency, frequency, dysuriafrequency, dysuria

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 Pupils dilates in 30-40mins,cycloplegia in 1-3 hrs last for a weekweek

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 Potent and fast acting (dilatation 30-60mins and last for

1day)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 Satisfactory for refraction testing in adults and for

fundoscopyfundoscopy

UsesUses As antisecretoryAs antisecretory

Preanaesthetic medication-(Atropine, glycopyrolate, Preanaesthetic medication-(Atropine, glycopyrolate, hyosine)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 Pylorospasm, gastric hypermotility, gastritis, gastric

dyspepsiadyspepsia Urinary frequency, urgency, enuresis in childrenUrinary frequency, urgency, enuresis in children dysmenorrheadysmenorrhea

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

Cholinergic Blocking Cholinergic Blocking Agents: Therapeutic Agents: Therapeutic

UsesUsesCNSCNS

Decreased muscle rigidity and muscle Decreased muscle rigidity and muscle tremorstremors

Parkinson’s diseaseParkinson’s disease Drug-induced extrapyramidal Drug-induced extrapyramidal

reactionsreactions

Cholinergic Blocking Cholinergic Blocking Agents: Therapeutic UsesAgents: Therapeutic UsesCardiovascularCardiovascularAffect 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 High doses: block inhibitory vagal effects

on on the SA and AV node pacemaker cellsthe SA and AV node pacemaker cells Result: increased heart rateResult: increased heart rate


UsesUsesAtropineAtropine

Used primarily for cardiovascular Used primarily for cardiovascular disordersdisorders

Sinus node dysfunctionSinus node dysfunction Symptomatic second-degree heart blockSymptomatic second-degree heart block Sinus bradycardia with hemodynamic Sinus bradycardia with hemodynamic

compromise (advanced life support)compromise (advanced life support)


Uses Uses RespiratoryRespiratoryBlocking 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

Cholinergic Blocking Cholinergic Blocking Agents: Therapeutic UsesAgents: Therapeutic UsesRespiratory 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


Uses Uses GastrointestinalGastrointestinalPSNS controls gastric secretions and PSNS controls gastric secretions and

smooth muscles that produce gastric smooth muscles that produce gastric motility.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

Cholinergic Blocking Cholinergic Blocking Agents: Therapeutic UsesAgents: Therapeutic UsesGastrointestinal agents are used to Gastrointestinal agents are used to

treat:treat: Peptic ulcer diseasePeptic ulcer disease Irritable bowel diseaseIrritable bowel disease GI hypersecretory statesGI hypersecretory states

Cholinergic Blocking Cholinergic Blocking Agents: Therapeutic Uses Agents: Therapeutic Uses GenitourinaryGenitourinary Relaxed detrusor muscles of the Relaxed detrusor muscles of the

bladderbladder Increased constriction of the Increased constriction of the

internal sphincterinternal sphincter Reflex neurogenic bladderReflex neurogenic bladder Incontinence Incontinence

Cholinergic Blocking Cholinergic Blocking Agents: Agents:

Side EffectsSide EffectsBody SystemBody System Side/Adverse EffectsSide/Adverse Effects

CardiovascularCardiovascular Increased heart rate, Increased heart rate, dysrhythmiasdysrhythmias

CNSCNS CNS excitation, CNS excitation, restlessness, restlessness, irritability, irritability, disorientation, disorientation, hallucinations, hallucinations, deliriumdelirium



EyeEye Dilated pupils, Dilated pupils, decreased decreased visual visual accommodation, accommodation, increased intraocular increased intraocular pressurepressure

GastrointestinalGastrointestinal Decreased salivation, Decreased salivation, decreased gastric decreased gastric

secretions, secretions, decreased motilitydecreased motility



GenitourinaryGenitourinary Urinary retentionUrinary retention

GlandularGlandular Decreased sweatingDecreased sweating

RespiratoryRespiratory Decreased bronchial Decreased bronchial secretionssecretions

anticholinergics (vk)

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