title: Epinephrine absorption after different routes of administration in an animal model.
abstract: BACKGROUND
  The administration of epinephrine is the most important initial treatment in systemic anaphylaxis.
  
  
  OBJECTIVE
  We wanted to determine the relationship between the route of epinephrine administration and the rate and extent of epinephrine absorption.
  
  
  METHODS
  In a prospective, randomized, five-way crossover study in rabbits, we measured plasma epinephrine concentrations before, and at intervals up to 180 min after epinephrine administration by intramuscular or subcutaneous injection, or by inhalation, with intravenous epinephrine and intramuscular saline as the positive and negative controls, respectively.
  
  
  RESULTS
  Maximum plasma epinephrine concentrations were higher, and occurred more rapidly, after intramuscular injection than after subcutaneous injection or inhalation, and were 7719+/-3943 (S.E.M.) pg/mL at 32.5+/-6.6 min, 2692+/-863 pg/mL at 111.7+/-30.8 min and 1196+/-369 pg/mL at 45. 8+/-19.2 min, respectively. Intravenous injection of epinephrine resulted in a plasma concentration of 3544+/-422 pg/mL at 5 min, and an elimination half-life (t(1/2)) of 11.0+/-2.5 min. In the saline control study, the endogenous epinephrine concentration peaked at 518+/-142 pg/mL.
  
  
  CONCLUSIONS
  In this model, absorption of epinephrine was significantly faster after intramuscular injection than after subcutaneous injection or inhalation. The extent of absorption was satisfactory after both intramuscular and subcutaneous injections. Neither the rate nor the extent of absorption was satisfactory after administration by inhalation.
authors.affiliation: Faculty of Pharmacy, University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: X
authors.initials: X
authors.lastname: Gu
authors.forename: F E
authors.initials: FE
authors.lastname: Simons
authors.forename: K J
authors.initials: KJ
authors.lastname: Simons
mesh_terms: D000042:Absorption; D000280:Administration, Inhalation; D000818:Animals; D019540:Area Under Curve; D004837:Epinephrine / Q000008:administration & dosage / Q000493:pharmacokinetics*; D007273:Injections, Intramuscular; D007279:Injections, Subcutaneous; D011817:Rabbits
chemical_list: D004837:Epinephrine