1. ANTI-ADRENERGIC DRUGS
PROF. A. K. SAKSENA

2. α ADRENOCEPTOR ANTAGONISTS
Phenoxybenzamine,
Phentolamine, Tolazoline, Ergotamine, DHE, Ergotoxine
Yohimbine(α2)
Non-selective older drugs; Block both α1 & α2
Prominent venodilation.

3. PHARMACOLOGICAL ACTIONS
1) Blood Vessels:- Severe dilation all over body. ↓ in t.p.r. and venous return Marked hypotension (+Postural hypot. also) Reflex tachycardia → d/t uninhibited release of NA → act on β1.

4. PHARMACOLOGICAL ACTIONS (contd.)
2) Kidney:- ↓ blood flow to kidneys
Reflex ↑ in secretion of renin
Activation of R-A-A system
↑ retention of Na/ water → ↑ blood volume
Drawbacks in Tt of HT:-
Intense vasodilation → ↑ Sym. Outflow
Cardiac stimulation (palpitation), Miosis, Diarr
Postural hypo, Nasal block, Impotence in male

5. NEWER DRUGS
- Prazosin (a>v.), Doxazosin, Terazosin, Alfuzosin - Selective α1 block only → No marked S/E - First dose effect is +. - BP is ↓- less severe - Tamsulosin:- Most recent drug (α1A, α1D ) On prostate only - BHP

6. THERAPEUTIC USES Hypertensive crisis Pheochromocytoma
Peripheral vascular disease
BHP (newer selective drugs)

7. β-ADRENOCEPTOR ANTAGONISTS
I. Non-selective:- Propranolol, Timolol, Labetalol (α also), Pindolol (Sym. mim.), Carvedilol (antioxidant). II. Cardio-selective:- Metoprolol, Atenolol, Betaxolol (α also), Celiprolol (β2 agonist)

8. PHARMACOLOGICAL ACTIONS
1) CVS:- A) Heart- ↓ in rate & force →↓ in cardiac work & O2 consumption Propanolol has Mem. Stabilizing action also. B) Bl. Vessels- Initially mild ↑ in PR. Later - ↓ in CO →↓ circulating volume V →↓PR Ultimately ↓ in BP– Sys./ Dias. (in HT mainly)

9. PHARMACOLOGICAL ACTIONS(contd.)
2) CNS:- Non specific β R in vasomotor area→ ↓ in sym. outflow. (Atenolol, Sotalol) 3) PNS:- Presynaptic β2 R at post gang. Sym. neuron terminals →↓ in release of NA.

10. PHARMACOLOGICAL ACTIONS(contd.)
4) Kidney:- β1 R at JG cells →↓ in release of
renin → ↓ activity in R-A-A system.
NOTE:- All the above 4 action contribute.
5) Respiratory sys:-
β2 in bronchi – blocked → bronchospasm
(esp. Asthmatics)

11. PHARMACOLOGICAL ACTIONS (contd.)
6) Metabolic:- β2 in liver/ muscle cells Block →↓ in glycogenolysis. 7) Skeletal Muscles:- Presynaptic β 2 at LMN →↓ release of ACh ↓ Blood flow to muscles → ↓ fatigue 8) Eye:- ↓ secretion of aqueous.

12. ADVERSE EFFECTS & CONTRAINDICATIONS
CHF may be precipitated, Sick sinus syndrome
Muscular weakness, fatigue
Bronchial asthma may be precipitated, COPD
Partial or complete heart block
Peripheral vascular disease → worsened. Cold hands & feet.
Sudden withdrawal → HT crisis
Not in Diabetics

13. THERAPEUTIC USES Hypertension
Angina Pectoris –Improve O2 supply/demand ratio
Cardiac arrhythmias- Propranolol
CHF
Myocardial Infarction- Secondary prophylaxis
↓ O2 consumption
Prevention of arrhythmias
Thyrotoxicosis

14. THERAPEUTIC USES(contd.)
Essential tremors
Anxiety
Glaucoma – Drops/ ocuserts
Pheochromocytoma - along with α blocker
Migraine