Pharmacological Actions of Sympathomimetic Drugs
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Questions and Answers

Which type of drugs indirectly activate adrenergic receptors by increasing the release of endogenous catecholamine?

  • Agonists
  • Parasympathetic drugs
  • Antagonists
  • Sympathomimetic drugs (correct)

What is the advantage of non-catecholamine agents over endogenous catecholamines?

  • Metabolized by COMPT and MAO enzymes
  • Shorter duration of action
  • Non-selective activity on adrenergic receptors
  • Prolonged duration of action (correct)

Which type of adrenergic receptor does noradrenaline have a strong affinity to?

  • β2 receptors
  • α2 receptors
  • α1 receptors (correct)
  • β1 receptors

What is the primary factor that limits the systemic use of endogenous catecholamines like adrenaline?

<p>Rapid metabolism by COMPT and MAO enzymes (B)</p> Signup and view all the answers

Which type of drugs act on all types of adrenergic receptors including α1, α2, β1, β2, and β3?

<p>Adrenaline (D)</p> Signup and view all the answers

What is the dose-dependent activity of dopamine on?

<p>D1, β1, and α1 receptors (D)</p> Signup and view all the answers

Which type of shock is adrenaline used to treat?

<p>Anaphylactic shock (C)</p> Signup and view all the answers

Which receptor does adrenaline act on to reverse the hypotension and bronchoconstriction caused by histamine in anaphylactic shock?

<p>α1 and β2 receptors (A)</p> Signup and view all the answers

In which type of shock is noradrenaline the preferred agent?

<p>Septic shock (A)</p> Signup and view all the answers

For what emergency use can adrenaline be given intramuscularly?

<p>Cardiac arrest (B)</p> Signup and view all the answers

What effect does adrenaline have when locally administered for its vasoconstrictor effect?

<p>Prolongs the action of anesthetic and prevents systemic absorption (D)</p> Signup and view all the answers

Which drug increases the release of noradrenaline from synaptic vesicles and can be used orally for its decongestant effect in case of common cold?

<p>Pseudoephedrine (B)</p> Signup and view all the answers

Why should pseudoephedrine be used cautiously in hypertensive patients?

<p>It causes tachycardia (B)</p> Signup and view all the answers

What does the selectivity on the α-receptors in selective α-receptor agonists help to avoid?

<p>Arrhythmogenic potential of activating the β1 receptors (B)</p> Signup and view all the answers

What is the main reason for using selective α-receptor agonists?

<p>To dissect the vascular effects from the cardiac actions (D)</p> Signup and view all the answers

What is the main scope of clinical uses of selective α-receptor agonists?

<p>Treatment of various cardiovascular conditions (A)</p> Signup and view all the answers

Flashcards

Indirect Adrenergic Receptor Activation

Drugs like amphetamines that indirectly activate adrenergic receptors boost the release of neurotransmitters like norepinephrine and epinephrine.

Non-Catecholamine Advantage

Non-catecholamine agents, unlike endogenous catecholamines, aren't broken down by COMT and MAO, giving them a longer lasting effect.

Noradrenaline Affinity

Noradrenaline has a strong preference for binding to α1 adrenergic receptors, triggering specific responses.

Endogenous Catecholamine Limitation

Endogenous catecholamines like adrenaline are rapidly metabolized, making their systemic use limited due to their short duration of action.

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Non-Selective Adrenergic Agonists

Non-selective adrenergic agonists activate all types of adrenergic receptors, including α1, α2, β1, β2, and β3.

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Dose-Dependent Dopamine Activity

Dopamine's effects on α1, β1, and D1 receptors depend on the dose administered.

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Adrenaline in Anaphylactic Shock

Adrenaline, used for anaphylactic shock, reverses hypotension and bronchoconstriction caused by histamine by acting on β2 receptors.

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Emergency Adrenaline Use

Adrenaline is used in emergencies like cardiac arrest and anaphylaxis to reverse the effects of shock.

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Adrenaline's Vasoconstrictor Effect

Applying adrenaline locally constricts blood vessels, reducing bleeding and prolonging the effects of local anesthetics.

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Pseudoephedrine's Action

Pseudoephedrine increases norepinephrine release from vesicles, offering decongestant benefits for colds, but caution is advised in hypertensive patients.

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Selective α-Receptor Agonists

Selective α-receptor agonists, unlike non-selective ones, avoid tachycardia and blood pressure increases.

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Selective α-Agonists' Purpose

Selective α-receptor agonists primarily promote vasoconstriction, increasing blood pressure for treatment of hypotension and nasal congestion.

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Clinical Uses of Selective α-Agonists

Selective α-receptor agonists are primarily used to treat hypotension (low blood pressure) and nasal congestion.

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Non-selective Adrenergic Agonists

Drugs that affect multiple types of adrenergic receptors are called non-selective adrenergic agonists.

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Adrenaline's Rapid Metabolism

Adrenaline is a type of catecholamine, a neurotransmitter that acts quickly but has a short duration of action.

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Noradrenaline for Septic Shock

Noradrenaline is preferred to treat septic shock, a severe complication of infection, due to its specific effects.

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Study Notes

Indirect Activation of Adrenergic Receptors

  • Indirectly activated adrenergic receptors increase the release of endogenous catecholamine, which is done by a type of drug called amphetamines.

Advantage of Non-Catecholamine Agents

  • Non-catecholamine agents have an advantage over endogenous catecholamines as they are not metabolized by catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO).

Noradrenaline Affinity

  • Noradrenaline has a strong affinity to α1 adrenergic receptors.

Limitation of Endogenous Catecholamines

  • The primary factor that limits the systemic use of endogenous catecholamines like adrenaline is their rapid metabolism and short duration of action.

Drugs Acting on All Adrenergic Receptors

  • Drugs that act on all types of adrenergic receptors, including α1, α2, β1, β2, and β3, are called non-selective adrenergic agonists.

Dose-Dependent Activity of Dopamine

  • Dopamine has a dose-dependent activity on α1, β1, and D1 receptors.

Adrenaline in Shock Treatment

  • Adrenaline is used to treat anaphylactic shock by reversing the hypotension and bronchoconstriction caused by histamine.
  • Adrenaline acts on β2 receptors to reverse the hypotension and bronchoconstriction caused by histamine in anaphylactic shock.
  • Noradrenaline is the preferred agent in septic shock.

Emergency Use of Adrenaline

  • Adrenaline can be given intramuscularly for anaphylactic shock or cardiac arrest.

Vasoconstrictor Effect of Adrenaline

  • When locally administered for its vasoconstrictor effect, adrenaline decreases bleeding and prolongs the duration of action of local anesthetics.

Pseudoephedrine

  • Pseudoephedrine increases the release of noradrenaline from synaptic vesicles and can be used orally for its decongestant effect in case of common cold.
  • Pseudoephedrine should be used cautiously in hypertensive patients due to its vasoconstrictor effect.

Selective α-Receptor Agonists

  • Selective α-receptor agonists help to avoid tachycardia and increase in blood pressure.
  • The main reason for using selective α-receptor agonists is to promote vasoconstriction and increase blood pressure.
  • The main scope of clinical uses of selective α-receptor agonists is in the treatment of hypotension and nasal congestion.

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Description

This quiz covers the pharmacological actions of sympathomimetic drugs, including their direct and indirect activation of adrenergic receptors. It also explores how these actions impact different body systems based on the type of receptors they act upon.

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