Adrenergic Agonists

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What type of receptors are stimulated by norepinephrine or epinephrine?

Adrenergic receptors (correct)

Cholinergic receptors

Dopaminergic receptors

GABA receptors

What are drugs that block activation of adrenergic receptors termed?

Sympatholytics (correct)

Sympathomimetics

Adrenergic agonists

Dopamine antagonists

Which of the following is NOT a direct-acting adrenergic agonist?

Indirect-acting agonist (correct)

Adrenaline

Noradrenaline

Dopamine

What is the role of dopamine in the context of adrenergic agonists?

A metabolic precursor of noradrenaline and adrenaline Signup and view all the answers

What is the term for drugs that activate adrenergic receptors?

Sympathomimetics Signup and view all the answers

Which of the following is an example of an indirect-acting adrenergic agonist?

Amphetamine Signup and view all the answers

What is the characteristic of catecholamines that allows them to directly activate α or β receptors?

High potency Signup and view all the answers

What enzyme is responsible for metabolizing catecholamines postsynaptically?

COMT Signup and view all the answers

What is the effect of oral administration of catecholamines?

They are inactivated and ineffective Signup and view all the answers

What is the structural feature of adrenergic agonists that affects their ability to differentiate between α and β receptors?

The number and location of OH substitutions on the benzene ring Signup and view all the answers

What is the location of the enzyme responsible for metabolizing catecholamines in the gut wall?

Gut wall Signup and view all the answers

What is the reason why norepinephrine is not useful in the treatment of bronchospasm or anaphylaxis?

It has a weak β2 activity Signup and view all the answers

What is the effect of norepinephrine on blood pressure?

It increases blood pressure Signup and view all the answers

What is the characteristic of catecholamines that limits their duration of action when given parenterally?

Rapid inactivation Signup and view all the answers

What is the result of the baroreceptor reflex stimulated by norepinephrine?

Bradycardia Signup and view all the answers

What is the effect of atropine on the heart rate response to norepinephrine?

It blocks the bradycardia and reveals a tachycardia Signup and view all the answers

What is the primary therapeutic use of norepinephrine?

Treatment of shock Signup and view all the answers

What is the effect of norepinephrine on the contractility of the heart?

It increases the contractility Signup and view all the answers

What is the primary effect of clonidine on sympathetic vasomotor centers?

Inhibition Signup and view all the answers

What is the most common side effect of albuterol, metaproterenol, and terbutaline?

Tremor Signup and view all the answers

What is the primary use of albuterol, metaproterenol, and terbutaline?

Management of acute asthma symptoms Signup and view all the answers

Why is abrupt discontinuation of clonidine avoided?

To prevent rebound hypertension Signup and view all the answers

What is the selectivity of albuterol compared to metaproterenol?

More selective for β2 receptors Signup and view all the answers

What is the off-label use of injectable terbutaline?

Suppression of premature labor Signup and view all the answers

What is tyramine's primary mechanism of action in the nerve terminal?

Displacing stored norepinephrine and releasing it into the synaptic space Signup and view all the answers

Why do small doses of catecholamines produce greatly magnified effects in an individual taking cocaine?

Cocaine potentiates the actions of epinephrine and norepinephrine by blocking their uptake Signup and view all the answers

What is the effect of MAOIs on the metabolism of tyramine?

MAOIs decrease the oxidation of tyramine in the gastrointestinal tract Signup and view all the answers

What is the mechanism of action of ephedrine and pseudoephedrine?

They stimulate both α and β receptors and enhance the release of stored norepinephrine Signup and view all the answers

What is the effect of cocaine on the duration of action of epinephrine and norepinephrine?

Cocaine increases the duration of action of epinephrine and norepinephrine Signup and view all the answers

What is the primary effect of tyramine on blood pressure?

Tyramine increases blood pressure by α1 agonist actions and β stimulatory effects Signup and view all the answers

What is the enzyme responsible for the conversion of tyrosine to dihydroxyphenylalanine in the adrenergic neuron?

Tyrosine hydroxylase Signup and view all the answers

What is the purpose of the amine transporter system in the adrenergic neuron?

To transport dopamine into synaptic vesicles Signup and view all the answers

What is the trigger for the release of norepinephrine from the synaptic vesicles?

An influx of calcium ions from the extracellular fluid Signup and view all the answers

What is the fate of norepinephrine released from the synaptic vesicles?

It binds to postsynaptic receptors on the effector organ or to presynaptic receptors on the nerve ending Signup and view all the answers

What is the effect of guanethidine on the release of norepinephrine?

It blocks the release of norepinephrine Signup and view all the answers

What is the rate-limiting step in the formation of norepinephrine?

The conversion of tyrosine to dihydroxyphenylalanine Signup and view all the answers

What is the effect of epinephrine on renal blood flow?

It decreases renal blood flow Signup and view all the answers

What type of receptors are responsible for epinephrine's effect on the liver and skeletal muscle?

β2 receptors Signup and view all the answers

What is the mechanism of epinephrine's hyperglycemic effect?

Increased glycogenolysis in the liver and increased release of glucagon Signup and view all the answers

What is the effect of epinephrine on mast cells?

It inhibits the release of allergy mediators such as histamine Signup and view all the answers

What is the effect of epinephrine on the bronchial smooth muscle?

It causes powerful bronchodilation Signup and view all the answers

Which of the following receptors is activated by epinephrine to cause renin release?

β1 receptors Signup and view all the answers

What is the primary effect of oxymetazoline on blood vessels supplying the nasal mucosa and conjunctiva?

Vasoconstriction Signup and view all the answers

What is the reason why prolonged use of dobutamine may lead to decreased effectiveness?

Tolerance may develop Signup and view all the answers

What is the mechanism by which clonidine decreases sympathetic outflow to the periphery?

It acts centrally on presynaptic α2 receptors to produce inhibition of sympathetic vasomotor centers. Signup and view all the answers

What is the primary effect of phenylephrine on blood pressure?

Increases both systolic and diastolic blood pressure Signup and view all the answers

What is the primary difference between albuterol and metaproterenol in their use as bronchodilators?

Albuterol is more selective for β2 receptors, while metaproterenol is less selective for β2 receptors. Signup and view all the answers

What is the potential adverse effect of oxymetazoline use for more than 3 days?

Rebound congestion and dependence Signup and view all the answers

What is the result of abruptly discontinuing clonidine therapy?

Rebound hypertension Signup and view all the answers

What is the primary receptor type targeted by phenylephrine?

α1 receptors Signup and view all the answers

What is the off-label use of injectable terbutaline in the United States?

As a uterine relaxant to suppress premature labor Signup and view all the answers

What is the potential side effect of oxymetazoline administration via the intranasal route?

Local irritation and sneezing Signup and view all the answers

What is the most common side effect of clonidine?

Sedation Signup and view all the answers

What is the reason why patients tend to develop tolerance to the side effect of tremor caused by albuterol, metaproterenol, and terbutaline?

Because the body adapts to the constant stimulation of β2 receptors Signup and view all the answers

What is the primary reason for avoiding concomitant use of MAOIs with direct-acting adrenergic agonists?

To reduce the risk of adverse cardiovascular effects Signup and view all the answers

What is the primary difference between salmeterol and formoterol in terms of their onset of action?

Salmeterol has a slower onset of action Signup and view all the answers

What is the recommended treatment approach for asthma when using LABAs?

Combination therapy with an inhaled corticosteroid Signup and view all the answers

What is the characteristic of LABAs that allows them to provide sustained bronchodilation over 12 hours?

Their long-acting duration of action Signup and view all the answers

What is the primary concern associated with the use of LABAs as monotherapy for asthma?

Increased risk of asthma-related deaths Signup and view all the answers

What is the difference in the duration of bronchodilation between albuterol and LABAs?

LABAs have a longer duration of action Signup and view all the answers