sympathomimetic

1. SYMPATHOMIMETICS

2. ADRENERGIC NERVOUS SYSTEM
Norepinephrine as the neurotransmitter
 Release from nerve terminals
 Adrenal medulla
 Regulates the functions in emergency, stress,
vigorous muscular activities
 Important regulator of heart and peripheral
vasculature

3. Neurotransmitters released by adrenergic nerves

4.  Stimulate the adrenergic nerves by mimicking
the action of norepinephrine ( NE )
 Increasing the concentration of ( NE )
CLASSIFICATION OF
SYMPATHOMIMETIC DRUGS

6. Pharmacological Targets in
Adrenergic System

7. ACCORDING TO MECHANISM OF ACTION
DIRECT ACTING
1-Epinephrine.
2-Norepinephrine.
3-Dopamine.
4-Isoprotrenol.
5-Dobutamine
6-Clonidine.
7-Phenylephrine.
INDIRECT ACTING
Re uptake inhibitors
1. TCAs
2. Cocaine
Releasers
1. Amphetamine
2. Ephidrine
3. Metaraminol
4. Tyramine
Metabolism
inhibitors
1.MAOi
2.COMTi

8. ACCORDING TO CHEMICAL NATURE.
CATECHOLAMINES
1-Epinephrine.
2-Norepinephrine.
3-Dopamine.
4-Isoproterinol.
5-Dobutamine.
NONCATACHOLAMINES
1-Amphetamine.
2-Tyramine.
3-Methylamphetamine.
4-Hydroxyamphetamine.
5-Ehidrine.
6-Phenylephrine.

9. Adrenoceptor SITE ACTIONS
1
Gq
IP3 and DAG
Vascular smooth muscle Contraction
Papillary dilator muscle Contraction
Pilomotor smooth
muscle
Contraction
Liver, adipose tissue Glycogenolysis,
gluconeogenesis
uterus / prostate Contraction
Urethral sphincter Contraction
bronchioles Contraction
GIT sphincters Contraction
Kidney Na+ reabsorption

10. Adrenoceptor SITE ACTIONS
2
Gi
↓ cAMP
Nerve terminals Inhibits NT release
platelets Stimulates aggregation
Vascular smooth
muscle
Contraction
Fat cells Inhibits lipolysis
Pancreas Inhibits insulin release
Glucagon release

11. Adrenoceptor SITE ACTIONS
β1
Gs
↑cAMP
Heart Stimulates rate and
force
Juxtaglomerular cells Stimulates rennin
release

12. Adrenoceptor SITE ACTIONS
β2
Gs
↑cAMP
Respiratory, uterine,
vascular smooth muscle
Relaxes
Liver Glycogenolysis
Pancreas Insulin release
Nerve terminals Tremors
Sphincters of GIT Contraction
Mast cells Histamine release
Kidney Renin release
β3
Gs
↑cAMP
Fat cells lipolysis

13. Adrenoceptor SITE ACTIONS
D
Gs or Gi
↑ or ↓ cAMP
Smooth muscles Dilate renal blood vessels

14. DRUG RECEPTOR AFFINITY
Norepinephrine 1 > 2.,., β1 >>>> β2, β3
Epinephrine 1 > 2 .,., β1 = β2, β3
Isoproterenol β1 = β2 >>>> 
Phenylephrine, methoxamine 1 > 2 >>>>> β
Clonidine, methyl NE 2 > > >>1 >>>>> β

15. DRUG RECEPTOR AFFINITY
Isoproterenol β1 = β2 >>>> 
Dobutamine β1 >>>> >>β2 >>>> 
Terbutaline, Albuterol Β2 >>>>> β1 >>>> 
Metaproterenol Β2 >>>>> β1
Dopamine , β and D
Amphetamine, Ephedrine Indirect acting

16. ORGAN SYSTEM EFFECTS
EYE
1 ------- pupillary dilator muscle ------- mydriasis
Increases the outflow of aq. humor ------ ↓ IOP
 2 ----- decreases production of aq humor ------ ↓ IOP
RESPIRATORY
β2 ---------- bronchodilation
 ------- decongestant effect

17. ORGAN SYSTEM EFFECTS
GIT
2 ------- salt and water absorption
β ----- relaxation
GENITOURINARY
β2 ---------- uterine relaxation
1 ----------- urinary continence, constriction of bladder
base
 -------------- ejaculation

18. ORGAN SYSTEM EFFECTS
EXOCRINE GLAND
Adrenoceptors --------- secretion of amylase and
water
increased saliva production
Sweat glands are regulated by sympathetic
cholinergic post ganglionic nerves

19. ORGAN SYSTEM EFFECTS
CNS
Nervousness
Tremors
Anxiety
Improved attention / alertness
Mood elevation
Insomnia
Euphoria
Anorexia
Psychotic behaviour

20. ORGAN SYSTEM EFFECTS
ENDOCRINE FUNCTIONS
β2 ------- insulin release, renin release
2 ------ inhibit insulin release, renin release
 Modulate the secretions of parathyroid hormone,
calcitonin, thyroxine and gastrin
METABOLIC EFFECTS
β1,2,3 ------- lipolysis
2 ------ inhibit lipolysis
1 ---- Glycogenolysis, gluconeogenesis, Na+ absorption
β 2 ------ Glycogenolysis

21. ORGAN SYSTEM EFFECTS
HEART
β1 ------- increased Ca influx ------- ↑ pace maker
activity and ↑ force of contraction
BLOOD PRESSURE
1 ------- ↑ vasoconstriction ------ ↑ TPR ----- ↑ BP ---
----- reflex bradycardia
β1 ----- ↑ pace maker activity and ↑ force of
contraction
β2 --------- vasodilation