This document discusses alpha blockers and central sympathoplegics. It describes the classification of alpha receptors based on selectivity, the pharmacological effects of alpha blockers including on the cardiovascular, renal, and urinary systems. Adverse effects of alpha blockers are outlined. Therapeutic uses of alpha blockers include for pheochromocytoma, hypertension, benign prostatic hypertrophy, and peripheral vascular disease. Alpha-2 selective adrenergic agonists like methyldopa and clonidine are described as central sympathoplegics. Methyldopa stimulates alpha-2 receptors in the central nervous system, lowering sympathetic outflow and reducing blood pressure and renin secretion. Its therapeutic uses include for pregnancy induced

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