title: Epinephrine absorption in children with a history of anaphylaxis.
abstract: BACKGROUND
  Prompt injection of epinephrine is the cornerstone of systemic anaphylaxis treatment. The rate of epinephrine absorption has not been reported previously in allergic children.
  
  
  OBJECTIVE
  Our objective was to study the clinical pharmacology of epinephrine in this population.
  
  
  METHODS
  We performed a prospective, randomized, blinded, parallel-group study in 17 children with a history of anaphylaxis to food, Hymenoptera venom, or other substances. We injected 0.01 ml/kg epinephrine solution (maximum 0.3 ml [0.3 mg]) subcutaneously, or 0.3 mg epinephrine intramuscularly from an autoinjector. Plasma epinephrine concentrations, heart rate, blood pressure, and adverse effects were monitored.
  
  
  RESULTS
  In nine children who received epinephrine subcutaneously, the mean maximum plasma epinephrine concentration (+/- SEM) was 1802 +/- 214 pg/ml, achieved at a mean time of 34 +/- 14 minutes (range, 5 to 120 minutes). Only two of the nine children achieved maximum plasma concentrations by 5 minutes. In eight children who received epinephrine intramuscularly, the mean maximum plasma concentration was 2136 +/- 351 pg/ml, achieved at a mean time of 8 +/- 2 minutes, which was significantly faster than the mean time at which maximum plasma concentrations were achieved after subcutaneous epinephrine injection (p < 0.05). Six of the eight children achieved maximum plasma concentrations by 5 minutes. The terminal elimination half-life was 43 +/- 15 minutes. No serious adverse effects were noted in any child.
  
  
  CONCLUSIONS
  In children, recommendations for subcutaneous epinephrine injection are based on anecdotal experience, and should be reevaluated in view of our finding of delayed epinephrine absorption when this route is used. This delay might have important clinical implications during an episode of systemic anaphylaxis. The intramuscular route of injection is preferable.
authors.affiliation: Department of Pediatrics and Child Health, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
authors.forename: F E
authors.initials: FE
authors.lastname: Simons
authors.forename: J R
authors.initials: JR
authors.lastname: Roberts
authors.forename: X
authors.initials: X
authors.lastname: Gu
authors.forename: K J
authors.initials: KJ
authors.lastname: Simons
mesh_terms: D000042:Absorption; D000707:Anaphylaxis / Q000097:blood / Q000188:drug therapy* / Q000378:metabolism*; D001794:Blood Pressure / Q000187:drug effects; D002648:Child; D002675:Child, Preschool; D004837:Epinephrine / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics*; D006207:Half-Life; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007273:Injections, Intramuscular; D007279:Injections, Subcutaneous; D011446:Prospective Studies
chemical_list: D004837:Epinephrine