Adrenergic

• Adrenergic drugs


  Medications that stimulate certain nerves in your body by mimicking the action of the chemical messengers epinephrine and norepinephrine or by stimulating their release
• Two broad classes of drugs that stimulate the adrenergic nervous system

  • Catecholamines
  • Noncatecholamines
• Catecholamines


  The body's naturally occurring neurotransmitters: norepinephrine, epinephrine, and dopamine
• Noncatecholamines


  Have actions similar to catecholamines but are more selective for certain types of receptors, not as fast acting, and have a longer duration of action
• Subdivisions of the adrenergic nervous system


  • Alpha receptors
  • Beta receptors
  • Dopaminergic receptors
• Alpha-1 receptors


  • Stimulation causes vasoconstriction of blood vessels
• Alpha-2 receptors


  • Serve as mediators of negative feedback, preventing further release of norepinephrine
• Beta-1 receptors


  • Stimulation causes an increase in heart rate
• Beta-2 receptors


  • Stimulation causes relaxation of smooth muscle in the bronchi, uterus, and peripheral arterial blood vessels
• Dopaminergic receptors


  • Stimulation in the brain improves symptoms associated with Parkinson's disease, and stimulation in the kidneys increases urine output
• Alpha- and beta-adrenergic blocking agents


  Act by plugging the alpha or beta receptors, preventing other agents from stimulating the specific receptors
• Nonselective beta antagonists


  • Propranolol, nadolol, pindolol, penbutolol, carteolol, sotalol, timolol
• Selective beta-1 blocking agents

  Exhibit action against the heart's beta-1 receptors (cardioselective) and do not readily affect the beta-2 receptors of the bronchi
• Selective beta-1 antagonists


  • Esmolol, metoprolol, acebutolol, betaxolol, bisoprolol, atenolol
• Labetalol and carvedilol


  Exhibit selective alpha-1 and nonselective beta-adrenergic blocking activity