Cathecolamine, Sympathomimetic Drugs

Cathecolamine, Cathecolamine, sympathomimetic sympathomimetic drugs & adrenergic drugs & adrenergic receptor antagonistreceptor antagonist

By : dr. Nur Hesti KusumasariBy : dr. Nur Hesti Kusumasari

Bagian Farmakologi Bagian Farmakologi

FK Univ. MalahayatiFK Univ. Malahayati

Cathecolamine, Cathecolamine, sympathomimetic drugssympathomimetic drugs Cathecolamines released by the sympathetic Cathecolamines released by the sympathetic

nervous system and adrenal medullanervous system and adrenal medulla Norepinephrine is the major neurotransmitter in Norepinephrine is the major neurotransmitter in

the peripheral sympathetic nervous systemthe peripheral sympathetic nervous system Epinephrine is the primary hormone secreted by Epinephrine is the primary hormone secreted by

the adrenal medullathe adrenal medulla The sympathomimetics are divided into subgroup The sympathomimetics are divided into subgroup

on the basis of their spectrum (on the basis of their spectrum (, , , or dopamine , or dopamine receptor affinity) or mode of action (direct or receptor affinity) or mode of action (direct or indirect)indirect)

Cathecolamine, Cathecolamine, sympathomimetic drugssympathomimetic drugs

Action of cathecolamine & sympathomimetic Action of cathecolamine & sympathomimetic drugs :drugs :

1)1) Peripheral excitatory actionPeripheral excitatory action (smooth muscle : (smooth muscle : blood vessels supplying skin, mucous blood vessels supplying skin, mucous membranes, salivary&sweat glands)membranes, salivary&sweat glands)

2)2) Peripheral inhibitory actionPeripheral inhibitory action (smooth muscle : (smooth muscle : wall of the gut, bronchus, blood supplying wall of the gut, bronchus, blood supplying skeletal muscle)skeletal muscle)

3)3) Cardiac excitatory action Cardiac excitatory action HR & force of contractionHR & force of contraction


4) 4) Metabolic actionMetabolic action glicogenolysis in liver & muscleglicogenolysis in liver & muscle

5) 5) Endocrine actionEndocrine action seretion of insulin, renin & pituitary seretion of insulin, renin & pituitary

hormoneshormones6) 6) CNS actionCNS action

Respiratory stimulation, Respiratory stimulation, psychomotor psychomotor activity, reduction in appetiteactivity, reduction in appetite


7) 7) Presynaptic actionPresynaptic action

Inhibition or facilitation of the release Inhibition or facilitation of the release

neurotransmitters (epinephrine & neurotransmitters (epinephrine &

acetylcholine)acetylcholine)

Cathecolamine, Cathecolamine, sympathomimetic drugssympathomimetic drugsOrgan System Effect :Organ System Effect : CNSCNS

Have a spectrum of stimulant effect (eg, amphetamine) : Have a spectrum of stimulant effect (eg, amphetamine) : anorexia, euphoria, and insomniaanorexia, euphoria, and insomnia

EyeEye dilator pupillary (mydriasis), dilator pupillary (mydriasis), IOP by non selective IOP by non selective agonistagonist

BronchiBronchirelaxing bronchial muscle by relaxing bronchial muscle by ββ22 agonist agonist

Gastrointestinal TractGastrointestinal Tractactivation of activation of and and ββ receptor leads to relaxation receptor leads to relaxation


Genitourinary TractGenitourinary Tract

increase sphincter tone (increase sphincter tone (). Uterine relaxation ). Uterine relaxation in pregnant women near term (in pregnant women near term (ββ2 agonist)2 agonist)

Vascular systemVascular system

depend on their dominant receptordepend on their dominant receptor

1 agonists1 agonists– (eg, phenylephrine) constrict skin – (eg, phenylephrine) constrict skin & splanchnic blood vessel and & splanchnic blood vessel and peripheral peripheral vasc resistane & venous returnvasc resistane & venous return


2 agonist2 agonist– (eg, clonidine) vasoconstriction (iv or – (eg, clonidine) vasoconstriction (iv or topically), accumulate in the CNS and topically), accumulate in the CNS and sympathetic outflow and blood pressure sympathetic outflow and blood pressure (orally)(orally)

agonistagonist– (– (2 agonist eg, terbutaline) 2 agonist eg, terbutaline) arterial arterial tone in the skeletal muscle vasc bed & tone in the skeletal muscle vasc bed & peripheral vasc resistane and arterial blood peripheral vasc resistane and arterial blood pressure. pressure. 1 have a little effect on vessels1 have a little effect on vessels

DopamineDopamine– vasodilation in the splanchnic and – vasodilation in the splanchnic and renal vasc bedrenal vasc bed

Cathecolamine, Cathecolamine, sympathomimetic drugssympathomimetic drugs HeartHeart

rate of cardiac pacemaker (normal and rate of cardiac pacemaker (normal and abnormal), abnormal), AV node conduction, AV node conduction, ardia force(ardia force(1 1 and and 2)2)

Cardiovacular actionsCardiovacular actionscause a reflex increase in vagal outflow (cause a reflex increase in vagal outflow ( and and ββ1)1)

Metabolic and hormonal effectMetabolic and hormonal effect renin secretion (renin secretion (ββ1), 1), insulin secretion ( insulin secretion (2) 2) and and glycogenolysis in the liver, stimulate glycogenolysis in the liver, stimulate lipolysislipolysis

Cathecolamine, Cathecolamine, sympathomimetic drugssympathomimetic drugsClinical UsesClinical Uses AnaphylaxisAnaphylaxis

Epinephrine is the DOC for the treatment of Epinephrine is the DOC for the treatment of anaphylactic shockanaphylactic shock

CNSCNSAmphetamine is widely used and abused for their Amphetamine is widely used and abused for their CNS effects. Indications : narcolepsy, attention CNS effects. Indications : narcolepsy, attention deficit disorder, weight reduction.deficit disorder, weight reduction.Abused: deferring sleep, mood-elevating, Abused: deferring sleep, mood-elevating, euphoria.euphoria.

Cathecolamine, Cathecolamine, sympathomimetic drugssympathomimetic drugs EyeEye

agonist (eg, phenylephrine) used to produce agonist (eg, phenylephrine) used to produce mydriasis without cycloplegia), reduce mydriasis without cycloplegia), reduce conjunctival itching and congestion e.c irritation conjunctival itching and congestion e.c irritation or allergy (Topically). Epinephrine used for or allergy (Topically). Epinephrine used for glaucomaglaucoma

BonchiBonchi 2-selective agonists are DOC in the treatment 2-selective agonists are DOC in the treatment of acute asthmatic bronchoconstriction. Short of acute asthmatic bronchoconstriction. Short ating (eg, terbutaline, albuterol, metaproterenol) ating (eg, terbutaline, albuterol, metaproterenol) for acute episodes, and long acting (eg, for acute episodes, and long acting (eg, salmeterol) for prophylaxissalmeterol) for prophylaxis


Cardiovascular ApplicationsCardiovascular ApplicationsAcute heart failure and shock (Acute heart failure and shock (1 agonists 1 agonists increase in blood fllow)increase in blood fllow)

Genitourinary TractGenitourinary Tract 2-agonists (ritodrine, terbutaline) are used to 2-agonists (ritodrine, terbutaline) are used to suppress premature labor, but the cardiac suppress premature labor, but the cardiac stimulation may be hazardous to mother and stimulation may be hazardous to mother and fetus.fetus.Ephedrine are used to improve urinary Ephedrine are used to improve urinary continence in children and the elderly with continence in children and the elderly with enuresis enuresis

Adrenergic Receptor Adrenergic Receptor antagonists antagonists (Adrenoceptor (Adrenoceptor Blockers)Blockers)

Separately into : Alpha-blockers and Separately into : Alpha-blockers and Beta-blockersBeta-blockers

Alpha-blockersAlpha-blockersClassification :Classification :1) 1) Irreversible, long actingIrreversible, long acting

eg, phenoxibenzamine is eg, phenoxibenzamine is 1 selective1 selective2) 2) Reversible, short actingReversible, short acting

eg, phentolamine is a competitive, reversible eg, phentolamine is a competitive, reversible blocking agent, nonselectiveblocking agent, nonselective

3) 3) Alpha1 selectiveAlpha1 selectiveeg, Prazosin, terazosin, doxazosin are eg, Prazosin, terazosin, doxazosin are selective, reversible selective, reversible 1 blockers1 blockers

4) 4) Alpha2 selectiveAlpha2 selectiveeg, Yohimbine, rauwolscine are eg, Yohimbine, rauwolscine are 2 selective 2 selective competitive antagonistscompetitive antagonists

Alpha-blockersAlpha-blockers

Pharmacokinetics Pharmacokinetics

These drugs are all active by the oral as These drugs are all active by the oral as well as parenteral routewell as parenteral route

Duration of action :Duration of action :

Phenoxybenzamine (48h)Phenoxybenzamine (48h)

Phentolamine (2-4 h)Phentolamine (2-4 h)

Alpha1 selective blockers (8-24 h)Alpha1 selective blockers (8-24 h)


Pharmacological EffectPharmacological Effect Nonselective blockersNonselective blockers : reduction in : reduction in

vascular tone with a reduction of both vascular tone with a reduction of both arterial and venous pressurearterial and venous pressure

Selective Selective blockers: blockers: reducing blood reducing blood pressurepressure


Clinical UsesClinical UsesNonselective Nonselective blockers:blockers:

Phenoxybenzamine used in the presurgical Phenoxybenzamine used in the presurgical management of phaechromocytoma (to reduce management of phaechromocytoma (to reduce hypertension)hypertension)Penile erection in men with erectile dysfunction Penile erection in men with erectile dysfunction (phentolamine or yohimbine)(phentolamine or yohimbine)

Selective Selective blockers:blockers:used in hypertension (prazosisn, terazosin, used in hypertension (prazosisn, terazosin, doxazosin)doxazosin)prevention in urinary retention in men with BPHprevention in urinary retention in men with BPH

Beta BlockersBeta Blockers

Classified into subgroup on the basis of Classified into subgroup on the basis of ββ1 selectivity, partial agonis activity, local 1 selectivity, partial agonis activity, local anesthetic action and lipid solubility.anesthetic action and lipid solubility.

ββ1 receptor selectivity (1 receptor selectivity (ββ1 blocks > 1 blocks > ββ2 2 blocks) eg, acebutolol, atenolol, esmolol, blocks) eg, acebutolol, atenolol, esmolol, metaprolol is advantage when treating in metaprolol is advantage when treating in patient with asthmapatient with asthma

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Cathecolamine, Sympathomimetic Drugs