What is the role of epinephrine in the treatment for croup?

Updated: Oct 09, 2019
  • Author: Germaine L Defendi, MD, MS, FAAP; Chief Editor: Russell W Steele, MD  more...
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Nebulized racemic epinephrine is a 1:1 mixture of dextro (D) isomers and levo (L) isomers of epinephrine with the L form (L-epinephrine) as the active component. Its use is typically reserved for patients in the hospital setting with moderate-to-severe respiratory distress. Epinephrine works by adrenergic stimulation, which causes constriction of the precapillary arterioles, thereby decreasing capillary hydrostatic pressure. This leads to fluid resorption from the interstitium and improvement in the laryngeal mucosal edema. [23] Epinephrine’s beta2-adrenergic activity leads to bronchial smooth muscle relaxation and bronchodilation. Its effectiveness is immediate with evidence of therapeutic benefit within the first 30 minutes and then, a lasting effect from 90-120 minutes (1.5-2 h).

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