Adrenergic Agonists Pharmacology Quiz

Adrenergic Agonists

• Definition: Adrenergic agonists are drugs that stimulate the activity of the sympathetic nervous system by binding to adrenergic receptors.
• Mechanism of Action: They mimic the action of endogenous catecholamines (e.g., norepinephrine, epinephrine) by binding to α1, α2, β1, β2, and β3 receptors.
• Effects:
  • α1 receptor stimulation: vasoconstriction, increased blood pressure
  • α2 receptor stimulation: decreased insulin secretion, increased glucagon secretion
  • β1 receptor stimulation: increased heart rate, contractility, and automaticity
  • β2 receptor stimulation: relaxation of smooth muscle, bronchodilation, and vasodilation
  • β3 receptor stimulation: lipolysis
• Examples:
  • Phenylephrine (α1 agonist): used to treat hypotension, nasal congestion, and priapism
  • Clonidine (α2 agonist): used to treat hypertension, attention deficit hyperactivity disorder (ADHD), and opioid withdrawal
  • Dobutamine (β1 agonist): used to treat heart failure and cardiogenic shock
  • Salbutamol (β2 agonist): used to treat asthma, chronic obstructive pulmonary disease (COPD), and bronchitis

Adrenergic Antagonists

• Definition: Adrenergic antagonists are drugs that block the activity of the sympathetic nervous system by binding to adrenergic receptors.
• Mechanism of Action: They counteract the effects of endogenous catecholamines by blocking α1, α2, β1, β2, and β3 receptors.
• Effects:
  • α1 receptor blockade: vasodilation, decreased blood pressure
  • α2 receptor blockade: increased insulin secretion, decreased glucagon secretion
  • β1 receptor blockade: decreased heart rate, contractility, and automaticity
  • β2 receptor blockade: bronchospasm, increased smooth muscle tone
  • β3 receptor blockade: decreased lipolysis
• Examples:
  • Prazosin (α1 antagonist): used to treat hypertension, benign prostatic hyperplasia (BPH), and post-traumatic stress disorder (PTSD)
  • Yohimbine (α2 antagonist): used to treat erectile dysfunction and xerostomia
  • Metoprolol (β1 antagonist): used to treat hypertension, angina pectoris, and heart failure
  • Propranolol (non-selective β antagonist): used to treat hypertension, angina pectoris, and anxiety disorders

Adrenergic Agonists

• Adrenergic agonists stimulate the sympathetic nervous system by binding to adrenergic receptors.
• They mimic the action of endogenous catecholamines (e.g., norepinephrine, epinephrine) by binding to α1, α2, β1, β2, and β3 receptors.

Effects of Adrenergic Agonists

• α1 receptor stimulation: vasoconstriction, increased blood pressure
• α2 receptor stimulation: decreased insulin secretion, increased glucagon secretion
• β1 receptor stimulation: increased heart rate, contractility, and automaticity
• β2 receptor stimulation: relaxation of smooth muscle, bronchodilation, and vasodilation
• β3 receptor stimulation: lipolysis

Examples of Adrenergic Agonists

• Phenylephrine (α1 agonist): used to treat hypotension, nasal congestion, and priapism
• Clonidine (α2 agonist): used to treat hypertension, attention deficit hyperactivity disorder (ADHD), and opioid withdrawal
• Dobutamine (β1 agonist): used to treat heart failure and cardiogenic shock
• Salbutamol (β2 agonist): used to treat asthma, chronic obstructive pulmonary disease (COPD), and bronchitis

Adrenergic Antagonists

• Adrenergic antagonists block the activity of the sympathetic nervous system by binding to adrenergic receptors.
• They counteract the effects of endogenous catecholamines by blocking α1, α2, β1, β2, and β3 receptors.

Effects of Adrenergic Antagonists

• α1 receptor blockade: vasodilation, decreased blood pressure
• α2 receptor blockade: increased insulin secretion, decreased glucagon secretion
• β1 receptor blockade: decreased heart rate, contractility, and automaticity
• β2 receptor blockade: bronchospasm, increased smooth muscle tone
• β3 receptor blockade: decreased lipolysis

Examples of Adrenergic Antagonists

• Prazosin (α1 antagonist): used to treat hypertension, benign prostatic hyperplasia (BPH), and post-traumatic stress disorder (PTSD)
• Yohimbine (α2 antagonist): used to treat erectile dysfunction and xerostomia
• Metoprolol (β1 antagonist): used to treat hypertension, angina pectoris, and heart failure
• Propranolol (non-selective β antagonist): used to treat hypertension, angina pectoris, and anxiety disorders

Test your knowledge of adrenergic agonists, their mechanism of action, and effects on the body. Learn about alpha and beta receptors and their role in pharmacology.