Adrenergic Antagonist Question and Answers

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Adrenergic Antagonist Important Notes

1. Sympathetic blocking drugs

Adrenergic Antagonist Sympathetic Blocking Drugs

2. Uses of alpha-blockers 

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

Read And Learn More: Pharmacology Question and Answers

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.

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 Drugs Included In It

Adrenergic Antagonist Short Answers

Question 1. Uses of alpha and beta blockers.

Answer:

Alpha 2 Adrenergic Antagonist

Adrenergic Antagonist Uses Of Alpha And Beta Blockers

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

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