43 Questions
What is the primary focus of learning objectives related to adrenergic drugs?
Mechanism of action, receptor affinities, and pharmacologic effects
What aspect of adrenergic drugs is crucial for understanding their observed cardiovascular effects?
Reflex homeostatic adjustments
Which factor is important for describing the significant pharmacokinetic properties of adrenergic drugs?
Metabolism and excretion
Which drug is approved for the treatment of urge incontinence due to hyperactive bladder?
Mirabegron
Which drug is used as a tocolytic agent to relax the pregnant uterus and suppress premature labor?
Ritodrine
Which drug is classified as a selective ß2 agonist and is used for the treatment of asthma and chronic obstructive pulmonary diseases (COPD)?
Terbutaline
Which drug is categorized as a nasal decongestant and a CNS stimulant?
Ephedrine
Which receptor does norepinephrine activate?
α1, α2 and ß1
What is the mechanism of action of isoproterenol?
Acts on ß1 and ß2 receptors
What is the effect of isoproterenol on bronchial and GI smooth muscle?
Relaxation
What is the primary therapeutic use of dopamine in cardiogenic shock?
Increased blood flow to kidney and splanchnic areas
Which receptor does dobutamine primarily act on?
ß1
What is the main effect of phenylephrine in the eye?
Mydriasis
What is the primary therapeutic use of phenylephrine?
Nasal decongestion
What is the effect of norepinephrine on pulse rate?
Decrease
What is the primary effect of epinephrine in open-angle glaucoma?
Decrease in intraocular pressure
What is the primary adverse effect of epinephrine?
Palpitation
What is the mechanism of action of dipivefrin?
Prodrug of epinephrine
What is the primary therapeutic use of dobutamine?
Congestive heart failure
Which receptors does epinephrine act on?
α1, α2, ß1, and ß2
What are the dose-dependent effects of epinephrine?
Low doses stimulate ß1 and ß2 receptors, high doses stimulate α1 and ß1 receptors
What are the metabolic effects of epinephrine?
Hyperglycemia, bronchodilatation, and smooth muscle relaxation
How are catecholamines like epinephrine inactivated?
By MAO and COMT
What is a therapeutic use of epinephrine?
Anaphylactic shock
Which type of adrenergic agonist is albuterol?
Non-catecholamine
How is epinephrine administered?
IV, SC, endotracheal tube, inhalation, and topical application
What effect does high-dose epinephrine have on blood vessels?
Vasopressor effects through α1 stimulation and vasodepressor effects through ß2 stimulation
What is the duration of action of epinephrine?
Brief
What effect does epinephrine have on renin secretion?
Stimulates
What is the classification of adrenergic agonists based on their mechanism of action?
Direct acting, indirect acting, and mixed acting
What is the effect of epinephrine on mast cell degranulation?
Inhibits
Which drug is used as a tocolytic agent to relax the pregnant uterus and suppress premature labor?
Terbutaline
Which drug is a false neurotransmitter that reduces central adrenergic tone and is used for its antihypertensive effects?
Methyldopa
Which drug is a local anesthetic and CNS stimulant that blocks uptake of NE in adrenergic neurons?
Cocaine
Which drug acts as a CNS stimulant, increasing the release of monoamines and blocking catecholamine reuptake, and is used in the treatment of ADHD and narcolepsy?
Amphetamine
Which drug is used as a spasmolytic in spinal cord spasticity?
Tizanidine
Which drug is used as a ophthalmic preparation to decrease intraocular tension in open-angle glaucoma?
Apraclonidine
Which drug releases large amounts of stored catecholamines from nerve terminals and is found in fermented foods, but is not clinically used?
Tyramine
Which drug acts directly on α and ß receptors and indirectly by releasing stored NE from nerve endings, and were previously used in bronchial asthma and nasal congestion?
Ephedrine
Which drug is categorized as a nasal decongestant and a CNS stimulant?
Pseudoephedrine
Which drug is a selective ß2 agonist and is used for bronchodilation and suppressing release of inflammatory mediators in the respiratory system?
Albuterol
Which drug is used for hypertension and withdrawal symptoms, and its adverse effects include sedation, bradycardia, sexual dysfunction, rebound hypertension, xerostomia, and constipation?
Clonidine
Which drug is a false neurotransmitter that reduces central adrenergic tone and is used for its antihypertensive effects?
Methyldopa
Study Notes
Adrenergic Agonists and Epinephrine Pharmacology
- Adrenergic agonists are classified into direct acting, indirect acting, and mixed acting types
- Direct acting adrenergic agonists include epinephrine, norepinephrine, phenylephrine, and albuterol
- Catecholamines like epinephrine and norepinephrine are rapidly inactivated by MAO and COMT
- Epinephrine acts on α1, α2, ß1, and ß2 receptors, producing cardiovascular effects
- Non-catecholamines like albuterol and clonidine act on α1 and ß2 receptors
- Epinephrine has dose-dependent effects, with low doses stimulating ß1 and ß2 receptors and high doses stimulating α1 and ß1 receptors
- At high doses, epinephrine induces vasopressor effects through α1 stimulation and vasodepressor effects through ß2 stimulation
- Epinephrine's metabolic effects include hyperglycemia, bronchodilatation, and smooth muscle relaxation in various organs
- It can also cause tremors and CNS effects, stimulate renin secretion, inhibit mast cell degranulation, and stimulate platelet aggregation
- Epinephrine is orally inactive, rapidly degraded by MAO and COMT, and has a brief duration of action
- Therapeutically, epinephrine is used for bronchospasm, anaphylactic shock, and as an adjunct to local anesthetics
- Epinephrine is administered via various routes including IV, SC, endotracheal tube, inhalation, and topical application
Adrenergic Drugs: Actions, Uses, and Side Effects
- Clonidine is an α2-selective agonist with multiple mechanisms of action, including activation of presynaptic α2-adrenoceptors and imidazoline receptors, used for hypertension and withdrawal symptoms.
- Clonidine's adverse effects include sedation, bradycardia, sexual dysfunction, rebound hypertension, xerostomia, and constipation.
- Apraclonidine is used as an ophthalmic preparation to decrease intraocular tension in open-angle glaucoma.
- Other α2 agonists include guanfacine, guanabenz, methyldopa (used for hypertension in pregnancy), and tizanidine (used as a spasmolytic in spinal cord spasticity).
- Direct-acting α-agonists like naphazoline, oxymetazoline, and xylometazoline are used as topical vasoconstrictors and nasal decongestants.
- Indirect-acting adrenergic drugs like amphetamine, tyramine, methyldopa, and ephedrine have various effects including CNS stimulation, vasoconstriction, and nasal decongestion.
- Amphetamine acts as a CNS stimulant, increasing the release of monoamines and blocking catecholamine reuptake, and is used in the treatment of ADHD and narcolepsy.
- Tyramine releases large amounts of stored catecholamines from nerve terminals and is found in fermented foods, but is not clinically used.
- Methyldopa is a false neurotransmitter that reduces central adrenergic tone and is used for its antihypertensive effects.
- Cocaine is a local anesthetic and CNS stimulant that blocks uptake of NE in adrenergic neurons.
- Ephedrine and pseudoephedrine act directly on α and ß receptors and indirectly by releasing stored NE from nerve endings, and were previously used in bronchial asthma and nasal congestion.
- Drugs having selective ß2 action include albuterol, pirbuterol, salmeterol, formoterol, terbutaline, and metaproterenol, and are used for bronchodilation and suppressing release of inflammatory mediators in the respiratory system.
Test your knowledge of adrenergic agonists and their pharmacology with this quiz. Explore the actions, uses, and side effects of various adrenergic drugs, including direct-acting, indirect-acting, and mixed-acting agents. Brush up on important details about specific medications such as epinephrine, clonidine, albuterol, and more.
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