In our previous post we have already talked about the normal adrenergic actions and now after reading and understanding them it will be very easy to understand these anti adrenergic drugs.
These anti adrenergic drugs will block the receptors on which adrenaline acts and so adrenaline will not be able to cause its effects and the disease state will be managed.
So talking about classification of Anti Adrenergic Drugs:-
A) Alpha Blockers
•Phenoxybenzamine– It blocks Alpha receptor of blood vessel so no more vasoconstriction will occur like used in case if pheochromocytoma when surgery is going to happen or even just after surgery their is high risk that this cancer if adrenaline gland will release high level of adrenaline into blood and can cause great vasoconstriction which will cause severe HTN so to prevent it, we can use this drug.Also in condition of BPH (Benign prostate hyperplasia) this drug can be used because it will block the alpha receptor of internal sphincter of bladder and urine outflow obstruction caused by BPH will be treated.A/E- It may interferes with ejaculation
•Phentolamine- Mainly used in case of pheochromocytoma.
•Prazosin- It is a short acting drug.Used in BPH+HTN
•Doxyzosin
•Terazosin Both Doxyzosin and Terazosin are same as Prazosin but these both drugs are long acting.
•Tamsulosin- It selectively act on the alpha receptor of internal sphincter of urinary bladder so is used extensively in BPH like conditions.
B)Beta Blockers
These drugs acts on the Beta blockersSome on both Beta 1,Beta 2 receptor, and some drugs blocks only beta 1 receptor.
1)Non selective beta blockers- They are non selective so they blocks both beta 1 as well as beta 2 receptors.So these drugs are very wisely used in patient’s.
Contraindications of beta blockers:-
Not used in asthma patients- Because they will block beta 2 receptor on Bronchus causing Bronchiospasm which will trigger asthma attack
Not used in pregnant mothers- Because they will block the beta 2 receptor on uterus and will cause contraction in uterus which may lead to abortion.
Not used in patients of HTN+Peripheral vascular disease(like Raynauds phenomena)
Not used in patients who have risk of erectile impotence
Not used in young patients with HTN- Because it will cause decrease in muscle power and so these young people will complaint of weakness after doing exercises,workouts.
Not used in patients with HTN+Dyslipidemia
Not used in Diabetic patients with HTN– or if used then are told to not skip the food(meal) at any cost.
These drugs are extensively used in patients of :-
HTN + Glaucoma- Because by blocking beta 1 of heart it will treat HTN and by blocking beta 2 of eye it will decrease IOP (intra occular pressure)
Graves disease– Beacuse in Graves disease T3 and T4 are realsed in high amount they causes increased secretion of adrenaline which causes Increased HR & BP.
Ischemic heart disease
In Tremors
As Prophylaxis in migraine
Sudden withdrawal of these drugs causes rebound HTN
•Propranolol
•Timolol- Used as eye drop,it decreases IOP to normal
•Sotalol- Used as anti arrythmic drug
•Pindolol– Not much used
2)Selective beta 1 blockers- They selectively blocks beta 1 receptor of heart and are hence cardioselective drugs
•Atenolol
•Metoprolol
•Nebivolol- They also acts on endothelial cells of blood vessels and causes release of NO which dilates the blood vessels.Also nabivolol have fast onset of action
•Bisoprolol- Highly cardioselective
•Celiprolol- It is a mild Bronchodilators well so can be used in patients of asthma with HTN.
•Acebutolol- It have intrinsic adrenergic activity due to this activity risk of rebound HTN after sudden withdrawal of this drug is minimal.
•Esmolol- Rapid and short acting drug.Used in emergency condition. (IV injection and Infusion)
C) Alpha+ Beta Blockers-
They blocks Alpha 1 receptor of blood vessel and beta 1 receptor of heart.
Used in-
Hypertensive emergency
Pregnancy induced HTN
Left ventricular dysfunction
•Labetolol
•Carvedilol
A/E of postural hypertension may be seen.
Contributor- Medico Anant Singh Nanda
