Sympathomimetic agents

• Drugs that mimic the action of adrenaline or noradrenaline are sympathomimetic drugs

  Classification

  
• alpha 1


  -Vasoconstriction

  -↑PR → ↑BP

  -uses:Topical - Nasal & ocular decongestion, mydriasis
• alpha 2


  -Inhibition of NE release

  -↓ In sym. tone
• beta 1

  • +ve chronotropic
  • +ve inotropic ↑ COP
• beta 2


  -Vasodilation

  -Bronchodilation – Drug Of Choice for Bronchial asthma Uterine relaxation ↑ glycogenolysis in muscle & liver,↑ Blood sugar
• Classification based on 


  agonist action on receptors

  
• Classification based on mechanism of action

  -Direct acting (Act on receptors): Epinephrine, Norepinephrine Isoprenaline, Salbutamol, Dopamine, Dobutamine ,Phenylephrine

  -Indirect acting: Tyramine, Amphetamine

  -Mixed action (direct & indirect acting): Ephedrine, Pseudoephedrine
• Classification based on Structure Catechol nucleus

  -Catecholamines: Epinephrine, Norepinephrine,Dopamine,Dobutamine Isoprenaline

  -Non-catecholamines :Ephedrine,Pseudoephedrine ,Amphetamine Phenylephrine

  Non-catecholamines are resistant to metabolism by MAO, COMT Hence, they are • Longer acting • Effective orally.