Easy and pharmacology

1. Classification
 s
Drugs
Actions
Epinephrine, nor-epinephrine,
phenylephrine, dopamine, dobutamine,
Albuterol, clonidine, frnoldopam,
formetrol, isoproterenol,
metaproterenol, salmetrol, terbutaline
Direct acting
Amphetamine
Cocaine
Indirect acting
Ephedrine
Pseudoephedrine
Direct and indirect acting (mixed
action)

2.  They can be grouped
 I- According to chemical structure into catechol amine & non catechol amine
 II. According to their mode of action
 direct acting
 Indirect acting
 Both direct as well as indirect acting
 III. According to duration of action into short intermediate and long acting
(e.g Adrenaline can belong to catechol amine, direct acting & short acting
Amphetamine is non catechol amine, indirect acting & long acting
 IV. According to the spectrum of receptors that they activate
 V. Therapeutic classification

3. I. According to their structure
CATECHOLAMINES:
1. Epinephrine
2. Nor epinephrine
3. Dopamine
4. Dobutamine
5. Isoproterenol
6. Isoetharine
7. Ethyl nor epinephrine
NON-CATECHOLAMINES
1. Phenylephrine
2. Ephedrine
3. Amphetamines
4. Pemoline
5. Methylphenidate HCL
6. Xylometazoline
7. Oxymetazoline

4. HO
HO ( (Benzene ring , -OH at 3 & 4 positions )
Absence of OH group may change potency as in Phenylephrine but
increases lipid solubility as in Ephedrine or Phenylephrine;
addition of amine group leads to increase in β-activity
HO OH
HO CH CH2 NH2 ( --- CH3 )
(Nor epinephrine ) ( epinephrine )

6. Steps in the enzymatic
synthesis of dopamine,
nor-epinephrine and
epinephrine. The
enzymes involved are
shown in red. Essential
cofactors in italics.
The final step occurs
only in the adrenal
medulla & in a few
epinephrine containing
neuronal pathways in
the brainstem.

7. II. According to mode of action:-
1) Direct acting drugs or direct agonists are those which themselves
directly activate adrenoceptors.
2) Indirectly acting or indirect agonist are the drugs whose action depend on
the release of endogenous catecholamines, which then act on adrenoceptors
The indirect agents may be of two types again
i) They can displace stored catecholamines from adrenergic nerve endings ,
they are Amphetamine like drugs & tyramine.
ii) They can inhibit reuptake of catecholamine already released(cocaine &
tricyclic antidepressants).
3) (Mixed) acting Some drugs have both direct and indirect actions
Ultimately Both types of drugs cause activation of adrenoceptors leading to
characteristic effects of endogenous catecholamines. Hence called
ADRENOCEPTOR ACTIVATING DRUGS

8. II. According to mode of action
A. DIRECTLYACTING
ON ADRENERGIC
RECEPTORS:
1. Epinephrine(Adrenaline)
2. Nor
epinephrine(Noradrenaline)
3. Dobutamine
4. Terbutaline
5. Isoproterenol(Isoprenaline)
6. Salbutamol
7. Phenylephrine
8. Clonidine
B. INDIRECTLY ACTING
ON ADRENERGIC
RECEPTORS:
1. Amphetamines
2. Atomoxetine
3. Reboxetine
4. Sibutramine
5. Duloxetine
6. Milnacipran
7. cocaine
C. MIXED ACTIVITY :
(Directly & indirectly
by releasing
catecholamines):
1. Dopamine
2. Ephedrine
3. Pseudo-ephedrine
4. Amphetamines
5. Phenyl
propanolamine

9. III. According to receptor-selectivity
A. ACTING ON ALPHA RECEPTORS: Alpha Agonists:
Can be α1 selective & α2 selective or α non selective:
(a). Alpha-1 selective (Relatively):
1. Methoxamine
2. Phenylephrine
3. Metaraminol
4. Midodrine
5. Mephenterimine

10. (b). Alpha-2 selective (Relatively):
1. Clonidine
2. Apraclonidine
3. Brimonidine
4. Tizanidine
5,6,7. Alpha methyl dopa, Guanfacine & Guanabenz
(Also used as central sympatholytics)
8. Dexmedetomidine (Prominent sedative effects &
used in anesthesia)
(c). Alpha-Non selective:
(on both alpha 1 & alpha 2 receptors equally):
1. Xylometazoline
2. Oxymetazoline

11. B. ACTING ON β RECEPTORS:
(a). β1 Agonist (selective Relatively)
(b). β2 Agonist (selective Relatively)
(c). β3 Agonist
(d). β non-selective (On both receptors):
(a). β1 Agonist (selective Relatively)
1. Dobutamine
2. Prenalterol

12. (b). β2 Agonist (selective Relatively)
1. Terbutaline
2. Albuterol (Salbutamol)
3. Metaproterenol
4. Ritodrine
5. Fenoterol
6. Bitolterol
7. Isoetharine
8. Long acting b2 agonists ie salmeterol
formoterol ,
9. New Ultralong β2 agonist
(i.e, Indacaterol, Olodaterol,
Vilanterol)

13. (c). β3 Agonist
1. Mirabegron
(d). β non-selective (On both receptors):
1. Isoproterenol (Isoprenaline)
Non selective drugs are now rarely used because of
adverse effects.
C. ACTING ON BOTH ALPHA & BETA RECEPTORS:
1. Epinephrine
2. Nor-epinephrine
3. Dopamine
4. Ephedrine
5. Pseudo ephedrine
6. Amphetamine

14. D. ACTING ON DOPAMINE RECEPTORS:
1. D1 agonist
 Fenoldopam
2. D2 agonist
 Bromocriptine

15. IV. Therapeutics Classification of
sympathomimetics
1. Used in bronchia asthma
Salbutamol, Terbutaline, Rimiterol, Isoprenaline, Ephedrine, Pseudoephedrine, Adrenaline,
Isoetharine
2. Used as nasal decongestants
Ephedrine, Naphazoline, Pseudoephedrine, Methoxamine, Phenylephrine, Xylometazoline,
Oxymetazoline
3. Used in acute & chronic orthostatic hypotension
Dopamine, Noradrenaline, Adrenaline, ephedrine, Metaraminol, Mephentermine
4. Used in Diseases of Heart i.e. Cardiac Application(In Cardiac arrest & Anaphylaxis)
Adrenaline, Isoprenaline, dobutamine, Ephedrine
5. Used for Hemostasis in Surgery (Alone or With local anaesthetic)
Epinephrine, Nor-epinephrine, Phenylephrine & other alpha agonists

16. 6. Used in prevention of premature labour
Salbutamol, Terbutaline, Isoxsuprine, Ritodrine
7. Used as vasodilator in peripheral vascular diseases
Isoxsuprine, Nylidrin
8. Used as mydriatrics
Ephedrine, Adrenaline, Phenylephrine
9. Used in Glaucoma
Apraclonidine, Bremonidine
10. Used as anorexics
Fenfluramine, Amphetamine, Dexamphetamine
11. Used as CNS stimulants
Amphetamine, Dexamphetamine, Methamphetamine

17. v. According to duration of action into
short intermediate and long acting
(e.g Adrenaline can belong to catechol amine,
direct acting & short acting
Amphetamine is non catechol amine, indirect
acting & long acting