PARASYMPATHOLYTICSBY

SYED FAYYAZUDDIN

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CONTENTSINTRODUCTION

CLASSIFICATION

PHARMACOLOGICAL ACTIONS

DRUGS

USES

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INRODUCTIONAcetylcholine.

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Receptor Location

M1 CNS, Postganglionic neurons.

M2 Myocardium, Smooth muscles.

M3 Exocrine glands, Smooth muscles.

M4 CNS

M5 CNS

M6 CNS

M7 CNS

M8 CNS

M9 CNS

M10 HEART

M11 BRONCHI

M12 BRONCHI

M13 CNS

NN Postganglionic neurons.

NM Skeletal muscles.

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MECHANISM OF ACTION

IP3 DAG cAMP Na+/K+

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Blocks action of Ach on autonomic effectors through

muscarinic receptors.

Competitive antagonists.

Prototype Atropine.

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Classification1. Natural alkaloids:

AtropineHyoscine

2. Semisynthetic derivatives:HomatropineHyoscine butyl bromideAtropine methonitrate.

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3. Synthetic compounds:

A.Mydriatics:

Tropicamide

B.Antisecretory-antispasmodic:

Dicyclomine.

Propanthaline.

Biperden.

C.Antiparkinsonian:

Tryhexyl phenidyl.

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GANGLIONIC BLOCKING AGENTS.

COMPETATIVE BLOCKERS

Hexamethonium

Mecamylamine

PERSISTANT DEPOLARISING BLOCKERS

Nicotine

Anticholinesterases04/10/2023 11

PHARMACOLOGICAL ACTIONSCNS

Stimulates many medullary centres. Vagal, respiratory and vasomotor. Anti-motion sickness property.

High dose cause Restlessness Disorientation Hallucinations Respiratory depression Coma.

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CVSprimarily in modifications of the heart rate:very low dose, it can give a slight cardiac slowingtherapeutic dose there is generally cardiac accelerationIt does not have vascular effects since there is no

parasympathetic tonus on the vessels but it inhibits vasodilatation caused by an intravenous injection of acetylcholine.

It does not induce modifications of arterial pressure in spite of increased cardiac rate.

in very high or toxic dose, it induces a fall of the arterial pressure by depression of the vasomotor centers

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PHARMACOLOGICAL ACTIONSEYS

MydriasisCycloplegiaPhotophobia.

SMOOTH MUSCLESRelaxationM3 BlokadeTone is reducedConstipationBronchodilation (asthma)

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PHARMACOLOGICAL ACTIONSGLANDS

SweatBronchial secretionsLacrinal secretions.Acid, pepsin and mucus in stomach.

BODY TEMPERATUREInhibition of sweatingTemperature regulatory centre in hypothalamusAtropine fever

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Sensitivity

Gastric glands and smooth muscle.

Smooth muscle intestine and bladder.

Eye, bronchial muscle and heart.

Saliva , sweat, bronchial secretions.

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TROPICAMIDEBlocks the response of sphincter muscle of iris and ciliary

muscles to cholinergic stimulation thus causing mydriasis.Stronger preparation also paralyzes accommodation.Acts within 15-30 m and duration is 3-8 h.typically used during eye examinations such as the dilated

fundus examination, but it may also be used before or after eye surgery.

ADVERSE REACTIONS: Blurred visionPhoto phobiaIncreased intraocular pressureDry mouthTachycardiaHeadacheAllergic reactionsNausea Vomiting

DICYCLOMINEIt is a smooth muscle relaxant. Irritable Bowel Syndrome (also known as spastic colon). It relieves muscle spasms and cramping in the gastrointestinal

tract by blocking the activity of acetylcholine on cholinergic (muscarinic) receptors on the surface of muscle cells.

ADVERSE REACTIONS:

Dry mouthTachycardiaHeadacheAllergic reactionsNausea Vomitingconfusion agitation

HEXAMETHONIUMGanglionic blockerN receptor antagonist, acts in autonomic ganglia.Does not have any effect on muscarinic Ach receptors.Acts at receptors at neuromuscular junction responsible for

skeletal muscle motor response.

ADVERSE EFFECTS : ConstipationUrinary retentionGlaucomaBlurry visionDecreased lacrymal secretionDry mouth (xerostomia)

USESAntisecretory

PreanaesthticThe main reasons for using anticholinergic drugs were

drying of secretions and protection against vagal over activity.

Blocks responses to vegal refluxes induced by sergical manipulations of visceral organs.

Peptic ulcerPulmonary embolism

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AntispasmodicSpactic constipationNervous and drug induced diarrhoea.

Asthama, COPD

Cardiac vagolytic Bradycardia

Central actionsParkinsonismMotion sickness

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ReferencesTripathi KD. Anticholinergic drugs.In Essentials of medical

Pharmacology. 5th ed. JP Brothers Medical publishers (P) Ltd: New Delhi; 2003. pp. 93-102.

Katzung, Bertram.G, Basic and clinical pharmacology.10th ed. Mc Graw Hill. USA(NY); 2006. pp. 482-9.

Goodman & Gilman’s, The Pharmacological Basis Of Therapeutics. 11th ed. Mc Graw Hill. USA(NY); 2006. pp. 121-9.

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