PHARMACOLOGY OF ADRENERGIC

NEURON BLOCKERS

Presentation by

Shahan ullah

Assigned by

Dr. Niaz Ali

ADRENERGIC NEURON BLOCKERS Reserpine Guanethidine Bretylium

MECHANISM

MECHANISM OF ACTIONS RESERPINE It blocks the Mg/ATP dependent

VESICULAR MANO AMINE TRANSPORTER(VMAT)

GUANATHEDINE/BRETYLIUM It inhibits nerve impulse coupled N.A

release from vesicles(bretylium). Displaces N.A from storage vesicles Engages and blocks the N.A reuptake at

axonal membrane.(REUPTAKE 1)

RESERPINEORGAN/SITE ACTION

CENTRAL NERVOUS YSTEM ↓ dopamine

↓ serotonin

↓ nor adrenaline

CARDIOVASCULAR SYSTEM ↓ cardiac output

↓ vascular resistance

GIT Ultimate increase motility

Ultimate increased secretions

Reproductive system Decrease in libido

Nasal region Turbinate lateral wall size increase

Eye Dilator pupillae are blocked

Metabolism Anti diabetogenic

THERAPEUTIC ACTION

RESERPINE

Anti-Hypertensi

ve

Anti-emeti

c

Anti-Psychoti

c

ADVERSE EFFECTS

Organ/site effect

CENTRAL NERVOUS SYSTEM DEPRESSION (suicidal tendency)

NIGHTMARES

EXTRA PYRAMIDAL (PARKINSON) EFFECTS

CARDIOVASCULAR SYSTEM MILD POSTURAL HYPOTENSION

GIT DIARRHOEA

ACIDITY

NASAL REGION NASAL CONGESTION

REPRODUCTIVE SYSTEM DELAYED EJACULATION

CONTRA INDICATIONS PEPTIC ULCER DEPRESSION

GUANETHIDINE.

Lowering of BP

Triphasic response

Biphasic response

Monophasic

response

GUANETHIDINE

ORGAN/SITE ACTION

CENTRAL NEROUS SYSTEM DOESN’T CROSS BBB

RENAL ↓INITIAL BLOOD FLOW, (regulatory action)

GASTRO INTESTINAL TRACT INCREASE MOTILITY(PSNS)

INCREASE SECRETIONS(PSNS)

EYE DECREASE I.O.T

MIOSIS

NASAL REGION INCREASE SIZE OF TURBINATE LATERAL WALLS (INCREASE CORONARY FLOW)

ADVERSE EFFECTS Postural hypotension Weakness Diarrhoea Delayed or retrograde ejaculation Nasal stuffiness It cause super sensitivity of receptors

leading to regulation of α1 receptors causing intense vasoconstriction (HTN crisis)

Fluid retention (long term use tolerance develops)

Worsening of CCF.

THERAPEUTIC PURPOSES ANTI HYPERTENSIVE(Last choice

therapy) For management of Pheochromocytoma

BRETYLIUM ACTIVITY Prolongs duration of ventricular action potential It prolongs the refractory period of ischemic heart

tissue and decreases its excitability(by blocking K+ channels)

Also blocks N.A release. THERAPEUTIC USE Anti- arrhythmic Anti-hypertensive ADVERSE EFFECTS Postural hypotension Bradycardia Nausea/Vomiting

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