Adrenergic agonists include adrenaline, noradrenaline, and other drugs that act on alpha and beta receptors. They have various effects depending on the receptor subtype activated and dose administered. Common uses include treating anaphylaxis, cardiac arrest, nasal congestion, and bronchodilation in asthma. Potential adverse effects include hypertension, arrhythmias, peripheral ischemia, and pulmonary edema at high doses due to cardiovascular effects. The kinetics and receptor selectivity determine appropriate routes of administration and clinical applications for each adrenergic agonist.

1. Adrenergic Agonists
Adrenaline
Epinephrine
Noradrenaline
Norepinephrine
β1>β2>α1>α2
Heart: β1(+ve ino,chrono,dromotropic) increase all cardiac properties
Low dose<0.1µg/kg :β2(vasodilatation in liver,coronary&skeletal muscles)
Blood
vessels High dose>0.1µg/kg :α1(vasoconstriction in skin&mucous membrane)
RT β2: potent bronchodilator
GIT
α1 on sphincters(closing) & β2 on walls(relaxation)
α2 presynaptic on parasympathetic nerve to wall A.Ch. (relaxation)
UT
α1 on sphincter of detrusor muscle (closing)
Hyperglycemia
β2 in liver (glycogenolysis &↑ glucagon)
α2 in pancreas (↓ Insulin)
Lipolysis β1 & β3 in adipocytes (↑lipase enzyme ↑FFA)
Uses
Drug of choice in Acute Anaphylactic shock (bronchspasm&vasodilatation)
Acute cardiac arrest
Local haemostatic to stop hemorrhage from nasal mucosa
Local anesthetic Vasoconstriction (↓bleeding & ↑duration of action)
Adverse
effects
β2 & β3 on walls of urinary bladder = detrusor muscle (relaxation)
β2 on walls of pregnant uterus (relaxation)
Indirect CNS disturbances as catecholamines can not pass BBB
Cardiac arrhythmias (tachycardia) Ventricular fibrellation
Gangrene of peripheral tissues due to severe vaso constriction
Cerebral hemorrage Net result of blood pressure (Hypertension)
Large dose
Pulmonary edema due to +ve inotropic & vasoconstriction
contra-indications
No.& sensitivity of β receptors (up regulation)
COMT = increase adrenaline in synapse
Beta blockers as in low dose, vasoconstriction occurs (Hypertension)
Cocaine as it prevents reuptak=incrase adrenaline&exaggerated CVS action
Diabetes due to low insulin
Hyperthyroidism
( ↑ T3 & T4 )
Non
selective
α & β
Releasers
α1>α2>β1
α 1(vasoconstriction &↑↑ Reflex bradycardia”- vechronotropic”)&β1(weak+veinotropic)
uses Cardiogenic shock & Severe Hypotension
contra-indications Bronchial astma as no effect on B2 & Local anethetic due to potent V.C.
side-effects similar to epiniphrine , Blanching&Sloughingof skin due to potent V.C
α2 in pancreas (↓ Insulin)
Kinetics
Not orally (destroyed by MAO) Not I.M. (no B2 effect) Not S.C.(potent V.C.)
Given I.V. Infusion Not bolus (due to short duration of action)
HOCM = IHSS
Kinetics
Given I.V. bolus in ICU not I.C.(still V.D.) I.M.(B2=V.D.) Inhalation(local B2 broncodilatation)
Not orally (destroyed by MAO) Not eye dps(little absorption& destroyed by alkaline tears)
Angina
If patiend take M-blocker, No reflex bradycardia occurs
Non selective
β1 & β2
Isoproterenol
Isoprenaline
Heart: β1(+ve ino,chrono,dromotropic) increase all cardiac properties
β2 (vasodilatation in liver,coronary & skeletal muscles)
systolic, diastolic,peripheral resistance Heart Rate
Systolic&Heart rate Diastolic&peripheral resistance
Kinetics
Destroyrd by COMT NOT by MAO
Acute bronchial asthma & Heart stimulant in ICU
uses
Dopamine
Low dose: D1=vaodilatation=incrase renal&visceral blood flow
Intermediate dose: β1 ("↑COP=+ve ino"&chronotropic effect)
High dose: α1 ( vasoconstriction=Hypertension )
Given orally & inhalation
Shock due to myocardialinfraction,Renal failure,Trauma
correct tissue perfusion rather than blood pressure
uses
kinetics
Destroyed by COMT&MAO into homovanillic acid
Given I.V. Infusion (short duration&dose dependent)
Selective β1
Dobutamine
"↑COP = +ve ino", dromotropic effect
Little change in H,R,=Not elevate O2demand for myocardium
uses
Acute CHF & Inotropic support after cardiac surgery
Adverse
effects
caution in atrial fibrillation to avoid ventricular fibrillation
Tolerance (down rgulation)
Selective β2
Ritordine
SABA
Salbutamol=albuterol, Pirbuterol& terbutaline
Acute asthma as MDIs (Rapid onset&Short duration)
due to +ve dromotropic of dobutamine
LABA
salmeterol & formoterol as single inhaled dose
Chronic astha (Slow onset &Long duration=12h)
Tocolytic(uterine relaxant) in premature labor
Noct urnal asthma & combined with corticosteroids
Noncatecholamines=pass BBB
Not hydrolized by MAO or COMT
Tachycardia(large dose=nonselective)Tremors,Tolerance(downregulation)
Nonselective
α 1 & α 2
Oxymetazoline
Nasal decongestant
Relief redness of eye
Vasoconstriction
side effect
Rebound
CNS depression at children
Selective α1
Phenylephrine
Methoxamine
Vasoconstriction=vasopressor=increase Blood Pressure(I.V.)
Nasal decongestant,Relief eye redness,Mydriatic
Reflex brady cardia (-ve chronotropic)
for supraventricular(atrial) tachycardia due to
Not Ventricular as no parasympathetic supply to ventricles
side effects
Hypertensive headache, nausea&vomiting
Clonidine
Brimonidine
Selective α2
Presynaptic
Eye dps (↓mydriasis of α1↓aq.humor of β2)
Not I.V.(α2 in blood vessels=sudden hypertension)
Given orally or as transdermal patches
Treat Hypertention &Withdrawal symptoms
VMC in CNS, sympathetic outflow(N.E.)
side-effect
sidation,salt&H2Oretention(give diuretic)
Reflex renin system=hypertensice crisis ‫متبطلوش‬
‫فجأة‬
Safe to renal failure (act centrally not peripherla)
Amphetamine
CVS: α (Hypertension) & β (Tachycardia)
CNS
dopamine&N.E.(stimulation)
Fatigue,Insomnia,Appetite
use
Attention Defficiency Hyperactivity Disorder
Narcolepsy
Contra-indication
Pregnancy,Epilipsy,cardiac proplems
Obesity ‫بالش‬
‫لمرضى‬
‫القلب‬
Tyramine
Noncaticholamine=pass BBB
addictive
contraindicated with MAO Inhibitors=vassopressor episodes
Cocaine
CNS stimulant&Local anethetic as eye dps
Inhibit N.E.reuptake
sympathetic activity
Mixed
Ephedrine
Pseudoephedrine
Noncatecholamines=pass BBB
Not hydrolyzed by MAO or COMT
Given orally
CNS stimulant opposing hypnotic effect of antihistamine
α & β
Agonists
broncho dilatation
N.E.
Nasal decongestant
Systolic & Diastolic blood pressure
CVS: α (Hypertension) & β (Tachycardia)
Cause Urine retention
OTC common cold drugs
Indirect Releaser
Reuptake Inhibitor
fermentated food= drug-food interaction
Diastolic blood pressure & peripheral resistance
Diastolic blood pressure & peripheral resistance
Systolic blood pressure & Heart Rate
Not hydrolized by COMT
treat hypotension due to inhaled halothane anethetic
over dose Anginal pain, tachycardia, nausea & vomiting