16 Questions
Which type of drugs indirectly activate adrenergic receptors by increasing the release of endogenous catecholamine?
Sympathomimetic drugs
What is the advantage of non-catecholamine agents over endogenous catecholamines?
Prolonged duration of action
Which type of adrenergic receptor does noradrenaline have a strong affinity to?
α1 receptors
What is the primary factor that limits the systemic use of endogenous catecholamines like adrenaline?
Rapid metabolism by COMPT and MAO enzymes
Which type of drugs act on all types of adrenergic receptors including α1, α2, β1, β2, and β3?
Adrenaline
What is the dose-dependent activity of dopamine on?
D1, β1, and α1 receptors
Which type of shock is adrenaline used to treat?
Anaphylactic shock
Which receptor does adrenaline act on to reverse the hypotension and bronchoconstriction caused by histamine in anaphylactic shock?
α1 and β2 receptors
In which type of shock is noradrenaline the preferred agent?
Septic shock
For what emergency use can adrenaline be given intramuscularly?
Cardiac arrest
What effect does adrenaline have when locally administered for its vasoconstrictor effect?
Prolongs the action of anesthetic and prevents systemic absorption
Which drug increases the release of noradrenaline from synaptic vesicles and can be used orally for its decongestant effect in case of common cold?
Pseudoephedrine
Why should pseudoephedrine be used cautiously in hypertensive patients?
It causes tachycardia
What does the selectivity on the α-receptors in selective α-receptor agonists help to avoid?
Arrhythmogenic potential of activating the β1 receptors
What is the main reason for using selective α-receptor agonists?
To dissect the vascular effects from the cardiac actions
What is the main scope of clinical uses of selective α-receptor agonists?
Treatment of various cardiovascular conditions
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.
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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