Sympathomimetic Drugs

2. Epinephrine
1-(3,4-dihydroxyphenyl)-N-methylaminoethanol
Non-selective
α1 agonist, β1 agonist, α2 agonist, β2 agonist.
Inactive when given by oral route as it undergoes enzymatic
degradation and first pass metabolism.
Uses:
 In acute bronchial asthma
 In cardiac arrest
 In glaucoma
 As adjuanct with local anesthetic
Side Effects
Hypertension, Tachycardia, Palpitation, Gangrene

3.  Non-selective α1 agonist, β1 agonist, α2 agonist.
 Little effect on β2 receptor.
 Less potent than epinephrine
Uses
 Vasoconstrictive so can be used as cardiac stimulant.
 As adjuanct to local anesthetic.

4.  Selective α1 agonist and no β activity
 Orally active
 Duration of action is twice as epinephrine because it lacks
catechol loeity so not metabolised by COMT.
Use
 In Hypotension
 As Nasal decongestant.
 As adjuanct to local anaesthetic to decrease absorption

5.  Selective α1 agonist.
 Belong to 2-arylimidazolines
 Vasoconstrictive effect
 Nasal and opthalamic decongestant
2-(1-naphthylmethyl)imidazoline Oxymetazoline
T/t of facial erythema

6.  Selective α2 agonist.
 Structural resemblance with L-DOPA thus produce α-methyl nor
epinephrine so instead of nor-epinephrine, it binds with receptor and
will not increase sympathetic outflow, thus lower B.P.
 Inhibit enzyme DOPA decarboxylase.
 Useful as antihypertensive agents in combination with diuretic.

7.  2-[(2,6-dichlorophenyl)amino]-2-imidazoline
 Selective α2 agonist.
 Orally as well as I/v active
 Interact specifically with α2 receptor and decrease sympathetic outflow.
 Used as anti-hypertensive agent and in migraine also.
 T/t of tourette syndrome (neuropsychiatric disorder with onset in childhood)
 For clonidine, basicity of guanidine group is decreased to 8 because of
inductive and resonance effect of dichlorophenyl ring. Thus, it will exist in non-
ionized form required to enter CNS and thus produce sedative effect
(Premedication before surgery)

8.  Selective β1 agonist.
 Used in the treatment of heart failure and cardiogenic shock on
the basis of its positive inotropic action.
 Active when given I/v

9.  Also known as isoprenaline.
 Non-Selective β agonist.
 No activity against alpha adrenergic receptors
 Treatment of bradycardia, heart block, and rarely for asthma.

10.  Selective β2 adrenergic receptor agonist.
 Used in management of asthma symptoms
 As Tocolytic (anti-contraction medication) to delay preterm labor for
up to 48 hours.
 Tertiary butyl group in terbutaline makes it more selective
for β2 receptors. Since there is no hydroxy group on position 4 of the
benzene ring, the molecule is less susceptible to metabolism by the
enzyme catechol-O-methyl transferase

11.  2- t-butylamino-1-[(3-hdroxymethyl-4-hydroxy)phenyl]ethanol
 Selective β2 adrenergic receptor agonist.
 Used in management of asthma symptoms and COPD
 Salbutamol has been used to treat acute hyperkalemia, as it stimulates
potassium flow into cells, thus lowering the potassium in the blood
 As Tocolytic (anti-contraction medication)
 Tertiary butyl group makes it more selective for β2 receptors. Since there is no
hydroxy group on position 4 of the benzene ring, the molecule is less
susceptible to metabolism by the enzyme catechol-O-methyl transferase

12.  Selective β2 adrenergic receptor agonist.
 Used in relief of bronchospasm in conditions such
as asthma and COPD.

13.  Drug that stimulates the sympathetic nervous system to release
adrenaline and nor-adrenaline.
Hydroxyamphetamine
 Used medically in eye drops to dilate pupil (mydriasis), so that
the back of the eye can be examined.
 Used as diagnostic agent for testing Horner’s syndrome
(damage of nerves of eyes)

14.  Optical active isomer of Ephedrine. Contains 2 chiral atoms so exist
in 4 optical isomers.
 α- and β2-adrenergic receptors, to cause vasoconstriction and
relaxation of smooth muscle in the bronchi, respectively.
 Decrease symptoms of nasal congestion (α- action) .
 Activation of β2-adrenergic receptors produces relaxation of smooth
muscle of the bronchi causing bronchial dilation and thus helpful in
asthma.
 Also use as anti-tussive.

15.  Used as nasal decongestant, appetite suppressant,
and psychostimulant medication

16.  Act directly on receptor and also effect release of nor-epinephrine.
 Ephedrine, a sympathomimetic amine, acts on part of
the sympathetic nervous system (SNS).
 It cause indirect stimulation of the adrenergic receptor system by
increasing the activity of norepinephrine at the postsynaptic α and β
receptors.
 Used to prevent low blood pressure during spinal anesthesia.
 Bronchodilator
 It has also been used for obesity by inducing thermogenesis.

17.  Metaraminol, also known as metaradrine, a stereoisomer of meta-
hydroxynorephedrine is a potent sympathomimetic amine used in
the prevention and treatment of hypotension.
 It is an α1-adrenergic receptor agonist with some β effect.
 Metaraminol is also used in the treatment of priapism (condition in
which a penis remains erect for hours in the absence of stimulation
or after stimulation has ended)