Adrenergic Antagonist Question and Answers

Adrenergic Antagonist Important Notes

1. Sympathetic blocking drugs

2. Uses of alpha-blockers 

• Pheochromocytoma
• Hypertension
• Peripheral vascular diseases
• Congestive cardiac failure
• Benign hypertrophy of the prostate

3. Abrupt withdrawal of beta-blocker after chronic use causes

• Rebound hypertension
• Worsening of angina
• Sudden death

Beta 2 Adrenergic Antagonist

Adrenergic Antagonist Long Essays

Question 1. Classify beta-adrenergic receptor blockers. Describe the pharmacological actions, uses and adverse effects of propranolol.

Answer:

Beta-adrenergic receptor blockers:

β-blockers are drugs that block the actions of catecholamines mediated through β -receptors.

Beta-Adrenergic Receptor Blockers Classification:

1. Nonselective

• Without intrinsic sympathomimetic activity
  • Propranolol, sotalol, timolol.
• With intrinsic sympathomimetic activity
  • Pindolol, oxprenolol
• With additional blocking property.
  • Labetalol, carvedilol.

Beta 2 Adrenergic Antagonist

2. Cardioselective

• Metoprolol, atenolol, bisoprolol, esmolol, betaxolol
• Propranolol-Propranolol is a first-generation non-selective β-blocker with intrinsic sympathomimetic activity.

Pharmacological actions:

1. CVS:

• Decreases heart rate, force of contraction and cardiac output.
• Decreases BP.
• Cardiac work and oxygen consumption are reduced.
• AV conduction is delayed
• Blocks cardiac stimulant action of adrenergic drugs.
• Improves exercise tolerance in angina patients.

Read And Learn More: Pharmacology Question and Answers

2. Blood vessels.

• Blocks vasodilation produced by isoprenaline.

3. Respiratory tract

• Blocks β2 receptors in bronchial smooth muscles
• Increases bronchial resistance.

4. CNS.

Mild central effects like behavioural changes, forgetfulness, increased dreaming and nightmares occur.

5. Local anaesthetic.

• Potent anaesthetic agent but not used due to irritation.

Beta 2 Adrenergic Antagonist

6. Eye:

• Reduces intraocular pressure.
• Decreases secretion of aqueous humour.

7. Metabolic:

• Blocks adrenergic ally-induced lipolysis.
• Inhibits glycogenolysis.

8. Sekeletal muscle.

• Inhibits adrenergic ally-provoked tremors.

B Adrenergic Antagonist

Beta-Adrenergic Receptor Blockers Uses:

• Hypertension
• Prophylaxis of exertional angina.
• Congestive cardiac failure.
• Dissecting aortic aneurysm.
• Cardiac arrhythmia.
• Myocardial infraction.
• Pheochromocytoma.
• Prophylaxis of migrane.
• Glaucoma.
• Anxiety.
• Essential tremor.
• Hypertrophic obstructive cardiomyopathy.

Beta-Adrenergic Receptor Blockers Adverse effects:

• Hypotension.
• Impairment of myocardial function.
• Cold extremities.
• Precipitate acute asthmatic attacks
• Fatigue, weakness.
• Abrupt withdrawal causes rebound hypertension.
• Impairment of carbohydrate tolerance.

B Adrenergic Antagonist

Adrenergic Antagonist Short Essays

Question 1. Adrenergic alpha-blockers.

Answer:

Adrenergic alpha-blockers are drugs that block the adrenergic responses mediated through alpha-adrenergic receptors.

Adrenergic alpha-blockers Classification:

1. Non-equilibrium.

• Phenoxybenzamine.

2. Equilibrium or competitive.

• Non-selective.
  • Ergot alkaloids – ergotamine, ergotoxine.
  • Hydrogenated ergot alkaloids – dihydro- ergotamine.
  • Imidazolines – tolazoline.
  • Miscellaneous – chlorpromazine
• α1- selective.
  • Prazosin, Terazosin, Doxazosin.
• α2 – selective. – yohimbine.

Adrenergic alpha-blockers Actions:

• Inhibits vasoconstriction, leads to vasodilatation and decreases BP.
• Enhances release of noradrenaline by α2 blocked
• Reflex tachycardia.
• Nasal stiffness and miosis.
• Increased intestinal motility.
• Reduced tone of smooth muscle.

Adrenergic alpha-blockers Uses:

• Pheochromocytoma.
• Hypertension.
• Secondary shock.
• Peripheral vascular diseases.
• Benign hypertrophy of the prostate.

Adrenergic alpha-blockers Adverse effects:

• Postural hypotension, palpitation.
• Nasal stiffness, miosis.
• Impaired ejaculation.
• Impotence.

Question 2. Cardioselective beta blockers.

Answer:

Cardioselective beta blockers Actions:

• Selectively block β1 receptors.
• Bronchospasm is less or negligible.
• Less interference with carbohydrate metabolism.
• Lower incidence of cold extremities.
• Impaired exercise performance.
• Lesser chances of peripheral vascular disease.

Drugs included in it:

Adrenergic Antagonist Short Answers

Question 1. Uses of alpha and beta blockers.

Answer:

Alpha 2 Adrenergic Antagonist

Question 2. Prazosin.

Answer:

It is a potent highly selective α1 blocker

Prazosin Actions:

• Blocks sympathetically mediated vasoconstriction.
• Causes fall in BP.
• Dilates arterioles more than veins which result in decreased peripheral vascular resistance and cardiac output

Prazosin Uses:

• Hypertension.
• Left ventricular failure.
• Raynaud’s disease.
• Prostatic hypertrophy.
• Improve urine flow thereby reducing residual urine in the bladder.

Question 3. Timolol.

Answer:

• It is a non-selective β blocker.
• It is short acting.
• Orally it is a potent β – blocker.
• Its ocular hypotensive action is smooth and well-sustained.

Timolol Uses:

1. Topically.

• In the treatment of glaucoma.

2. Orally.

• Hypertension.
• Angina
• Prophylaxis of myocardial infarction.

Alpha 2 Adrenergic Antagonist

Question 4. Name cardioselective p blockers.

Answer:

• Cardioselective beta blockers:
• Metoprolol – bisoprolol – celiprolol
• Atenolol esmolol – nebivolol.
• Acebutolol – betaxolol.

Question 5. Propranolol is contraindicated in bronchial asthma Why?

Answer:

1. Blockade of β2 receptors of smooth muscles by propranolol causes.
2. Increases in airway resistance.
3. Precipitation of acute attacks in asthmatics.
4. Worsens chronic obstructive lung diseases.
   • Thus, it is contraindicated in bronchial asthma.

Question 6. Labetalol.

Answer:

Labetalol is the first adrenergic antagonist capable of blocking both α and β receptors.

• It is effective orally.

Labetalol Actions:

• Vasodilation
• Fall in BP
• Reduction in cardiac output, heart rate, and peripheral vascular resistance.

Alpha 2 Adrenergic Antagonist

Labetalol Uses:

• Pheochromocytoma.
• Clonidine withdrawal.
• Essential hypertension.

Labetalol Adverse effects:

• Postural hypotension.
• GI disturbances.

Viva Voce:

Beta-blocker is contraindicated in asthmatic patients