Pharmacology ANS

1. ALPHA BLOCKERS &CENTRAL
SYMPATHOPLEGICS
DR FOUZIA

2. 3/10/2023 ANS 2

3. 3/10/2023 ANS 3

4. CLASSIFICATION OF α-RECEPTORS
BASED ON RECEPTOR SELECTIVITY:
A- α1 SELECTIVE
Prazosin, Terazosin, Doxazosin, Tamsulosin
B- α2 SELECTIVE
Tolazoline, Yohimbine
C- NON-SELECTIVE (α1, α2 )
Phentolamine(reversible) , Phenoxybenzamine (irreversible)
3/10/2023 ANS 4

5. PHARMACOLOGICAL EFFECTS OF α-BLOCKERS
A-CVS:
Blockage of α1 receptors in peripheral blood vessels
1-Hypotension
2-Tachycardia
B-EYES AND NOSE
Nasal Congestion:
Blockade of α1 receptors in nasal blood vessels
Miosis:
Blockage of α1 receptors of radial muscles of iris

6. PHARMACOLOGICAL EFFECTS OF α-BLOCKERS
C-KIDNEY:
Hypotension (α blockage) ↓ renal blood flow → ↓GFR
D-URINARY BLADDER:
1-Relaxation of smooth muscle of bladder trigone, sphincter and
prostate
E- α blockers can inhibit ejaculation

7. ADVERSE EFFECTS OF α-BLOCKERS
1-Orthostatic hypotension
First dose syncope or First dose effect (Prazosin)
2-Tachycardia
3-Nasal Congestion
4-Inhibition of ejaculation

8. THERAPEUTIC USES OF α-BLOCKERS
1-Pheochromocytoma
2-Chronic hypertension
3-Benign prostatic hypertrophy (BPH)
4- Peripheral vascular disease

9. CENTRAL SYMPATHOPLEGICS

10. α2 SELECTIVE ADRENERGIC AGONISTS
Methyldopa
Clonidine
Apraclonidine
Brimonidine
Guanfacine
Guanabenz

12. METHYL DOPA
1-Methyl dopa is an analogue of DOPA, (precursor of dopamine (DA)
and NA).
2-It is produced as a prodrug, and needs to be activated.
3-It is actively transported to brain adrenergic neuron terminals, with the
help of NET
4-It stimulates α2 receptors in CNS leading to ↓ in sympathetic outflow

13. PHARMACOLOGICALACTIONS OF METHYL DOPA
1-CVS
1-↓ in TPR and ↓ in BP.
2-Kidneys
↓Renin secretion

14. THERAPEUTIC USES OF METHYL DOPA
1-Pregnancy induced hypertension
2-Pre-eclampsia or eclampsia

15. ADVERSE EFFECTS OF METHYL DOPA
1-Sedation
2-Dry mouth
3-Extra pyramidal signs
4-Positive Coomb’s test
5-Hepatotoxicity
6-Nasal congestion