This article is to discuss the use of Alpha and Beta blockers in the management of cases of hypertension regarding types,mechanism of action,pharmacological action, indications and side effects of the drugs .
A. Beta Blockers
Mechanism of action
- Negative inotropic .... -- COP --> -- BP
- Negative chronotropic .... -- COP --> -- BP
- Inhibition of renin release .
1. NON selective β1 & β2 :
- lnderal , at least 80 mg - 120 mg /d .
- Carvedilol 12.5-25 mg/d "Dilatrend" It is non selective with vasodilator properties, it can be used in patients with peripheral vascular disease .
2. Selective β1 :
- Atenolol. (Tenormin) Tablet. 50, 100 mg, dose (25mg - 200 mg/d) .
- Bisoprolol (Concor) tablets 2.5, 5, 10 mg.
B. Alpha Blockers
* Prazocin ( Minipress)
- Action : Arterial vasodilator and venodilator.
- Uses :
- Heart failure.
- Hypertension .
- Peripheral vascular diseases.
Side effects of alpha blockers :
First dose phenomenon (with 2 hours of the first dose):
i.e first dose causes marked vasodilatation which leads to syncope or postural hypotension.
(To avoid, start with low dose, at home and on going to bed, also withhold diuretics and BB).
* Other a-blockers e.g doxazosin (cardura) 1-4 mg/d, or terazosin (Itrin) 2-5 mg/d, they mainly used for senile prostate.
Labetalol (100-600 mg/12 hr) is an agent that has combined a and B blocking properties, it can be used in hypertension with pregnancy. Bronchospasm and vomiting are its main side effects.