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Questions and Answers
Which drug is indicated for the treatment of glaucoma?
Which drug is indicated for the treatment of glaucoma?
Which drug has primarily replaced Phenylpropanolamine?
Which drug has primarily replaced Phenylpropanolamine?
What is the main action of Clonidine?
What is the main action of Clonidine?
Which drug category does Tizanidine belong to?
Which drug category does Tizanidine belong to?
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What is a common feature of α1 receptor agonists?
What is a common feature of α1 receptor agonists?
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Which of the following drugs is primarily used to manage spasticity?
Which of the following drugs is primarily used to manage spasticity?
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Which drug is known to act on presynaptic receptors to decrease blood pressure?
Which drug is known to act on presynaptic receptors to decrease blood pressure?
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Which drug's use is linked to illicit manufacture of shabu?
Which drug's use is linked to illicit manufacture of shabu?
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Which of the following drugs is not primarily an adrenoreceptor agonist?
Which of the following drugs is not primarily an adrenoreceptor agonist?
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What is the primary action of Salbutamol (Albuterol)?
What is the primary action of Salbutamol (Albuterol)?
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Which catecholamine is the primary neurotransmitter in nerve endings?
Which catecholamine is the primary neurotransmitter in nerve endings?
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Which drug is classified as a long-acting bronchodilator with a rapid onset of action?
Which drug is classified as a long-acting bronchodilator with a rapid onset of action?
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Which of the following drugs is a tocolytic agent used to arrest premature labor?
Which of the following drugs is a tocolytic agent used to arrest premature labor?
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What is a significant characteristic of catecholamines regarding absorption?
What is a significant characteristic of catecholamines regarding absorption?
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Which drug is known for having anabolic action?
Which drug is known for having anabolic action?
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What is an effect of the drug Isoxsuprine?
What is an effect of the drug Isoxsuprine?
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Which route of administration is commonly used for catecholamines due to their poor oral absorption?
Which route of administration is commonly used for catecholamines due to their poor oral absorption?
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What distinguishes long-acting bronchodilators from short-acting ones?
What distinguishes long-acting bronchodilators from short-acting ones?
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Which catecholamine is produced in the adrenal medulla?
Which catecholamine is produced in the adrenal medulla?
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What is tachyphylaxis in relation to drug response?
What is tachyphylaxis in relation to drug response?
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What does refractoriness refer to in drug therapy?
What does refractoriness refer to in drug therapy?
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Which process specifically involves only agonist-occupied receptors?
Which process specifically involves only agonist-occupied receptors?
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What is the role of G-protein-coupled receptor kinase (GRK) in homologous desensitization?
What is the role of G-protein-coupled receptor kinase (GRK) in homologous desensitization?
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What happens to receptors after repeated activation by an agonist?
What happens to receptors after repeated activation by an agonist?
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How does homologous desensitization occur physically?
How does homologous desensitization occur physically?
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What is a characteristic feature of catecholamines?
What is a characteristic feature of catecholamines?
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What is likely the clinical significance of refractoriness when using sympathomimetic drugs?
What is likely the clinical significance of refractoriness when using sympathomimetic drugs?
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In which scenario is tachyphylaxis most likely to occur?
In which scenario is tachyphylaxis most likely to occur?
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What result does receptor phosphorylation lead to in terms of receptor activity?
What result does receptor phosphorylation lead to in terms of receptor activity?
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What is a primary effect of sympathomimetic drugs on the eye?
What is a primary effect of sympathomimetic drugs on the eye?
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Which receptor activation leads to ejaculation in the male reproductive system?
Which receptor activation leads to ejaculation in the male reproductive system?
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What condition was the patient in the case diagnosed with?
What condition was the patient in the case diagnosed with?
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What is a common adverse effect associated with the stimulation of adrenoceptors?
What is a common adverse effect associated with the stimulation of adrenoceptors?
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What immediate treatment was given to the patient experiencing respiratory distress?
What immediate treatment was given to the patient experiencing respiratory distress?
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Which receptor is primarily responsible for the vascular response after epinephrine administration?
Which receptor is primarily responsible for the vascular response after epinephrine administration?
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What is hypokalemia partly due to?
What is hypokalemia partly due to?
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What potential consequence can occur due to intense activation of 𝛼1 receptors?
What potential consequence can occur due to intense activation of 𝛼1 receptors?
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Which symptom is NOT associated with anaphylactic reactions?
Which symptom is NOT associated with anaphylactic reactions?
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What role do selective 𝛼2 agonist drugs play in ocular treatment?
What role do selective 𝛼2 agonist drugs play in ocular treatment?
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Which receptor activation is responsible for bronchodilation?
Which receptor activation is responsible for bronchodilation?
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What effect is expected from the activation of 𝛼-receptors?
What effect is expected from the activation of 𝛼-receptors?
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Which sympathomimetic drug is classified as a direct-acting agent?
Which sympathomimetic drug is classified as a direct-acting agent?
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Which adrenergic agonist is the most potent stimulant of hepatic glycogenolysis?
Which adrenergic agonist is the most potent stimulant of hepatic glycogenolysis?
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Which aspect does Epipen primarily reverse in anaphylaxis?
Which aspect does Epipen primarily reverse in anaphylaxis?
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What is a significant use of sympathomimetics during resuscitation?
What is a significant use of sympathomimetics during resuscitation?
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Study Notes
α1 Receptor Agonists
- Clonidine: Acts centrally on presynaptic receptors to decrease sympathetic outflow, lowering blood pressure.
- Methyldopa: Primarily replaced by Phenylephrine due to high dose risks.
- Guanfacine, Guanabenz: Reduce sympathetic activity and lower blood pressure.
- Apraclonidine, Brimonidine: Indicated for glaucoma treatment.
- Pseudoephedrine: Used mainly for its illicit manufacture; not its therapeutic effects.
- Tizanidine: Functions as a muscle relaxant for spasticity from cerebral or spinal disorders.
- Other examples include Mephentermine and Metaraminol.
Selective β1 Receptor Agonists
- Salbutamol (Albuterol): Promotes bronchodilation by relaxing bronchial smooth muscle.
- Salmeterol: Long-acting bronchodilator with a slower onset.
- Formoterol: Long-acting with rapid onset.
- Indacaterol, Olodaterol, Vilanterol: Ultra-long-acting agents.
- Clenbuterol: Exhibits anabolic effects.
- Ritodrine: Tocolytic agent to arrest premature labor.
- Isoxsuprine: Acts as a vasodilator for peripheral vasospastic diseases.
Mechanisms and Pharmacology
- Tachyphylaxis: Rapid, acute tolerance to drugs; often noted with indirectly-acting sympathomimetics.
- Refractoriness: Therapeutic failure to respond to treatment due to tolerance development.
- Homologous Desensitization: Loss of responsiveness occurs specifically at agonist-occupied receptors due to repeated exposure.
Adverse Effects
- Common side effects attributable to adrenoceptor stimulation include:
- Restlessness
- Headaches
- Tremors
- Cardiac effects such as palpitations, tachycardia, and arrhythmia.
- Severe reactions can lead to cerebral hemorrhage from intense α1 receptor activation.
Use in Anaphylaxis
- Epinephrine is used to reverse anaphylactic reactions, engaging α1, β1, and β2 receptors.
- Autoinjectors (e.g., Epipen) are available for self-administration.
- Can act on vascular systems and enhance the effects of local anesthetics by reducing systemic absorption.
Potency and Receptors
- β2 receptor agonists include Salbutamol, Terbutaline, and Formoterol; effective for bronchodilation.
- β3 receptor agonists like Mirabegron and Vibegron are relevant for metabolic processes.
- Receptor nonselectivity may cause drugs to act on multiple receptor subtypes, impacting efficacy and side effects.
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Description
This quiz focuses on the examples of α1 receptor agonists, highlighting their features and clinical applications. It examines specific drugs like Clonidine and Methyldopa, along with their mechanisms of action and potential risks. Ideal for students studying pharmacology or medicine.
