​​Direct Acting Agents

  • Phenylepherine
  • Epinephrine
  • Dobutamine
  • Norepinephrine

​​Indirect Acting Agents

  • Ephedrine ( Primary Direct acting)

Indirect acting agents stimulate release of norepinephrine from the nerve terminals.

  • Beta 1 receptor stimulation results in increased chronotropism, inotropism, stroke volume, and cardiac output.
  • Alpha 1 receptor stimulation increases SVR.
  • This leads to increased myocardial oxygen consumption.