title: The effects of enalapril and spironolactone on terbutaline-induced hypokalemia.
abstract: OBJECTIVE
  To investigate whether enalapril (E) 10 mg and spironolactone (S) 100 mg attenuate the hypokalemic effect of inhaled terbutaline (T).
  
  
  METHODS
  Randomized single-blind crossover. Subjects received the following treatment combinations: (a) placebo (P), (b) T alone, (c) T + E, or (d) T + S.
  
  
  METHODS
  University Department of Clinical Pharmacology.
  
  
  METHODS
  Twenty healthy volunteers (ten male, ten female) of mean age 22.8 +/- 3.1 years.
  
  
  METHODS
  Serum potassium, magnesium, ECG changes (R-R interval, T wave, and QTc interval) for 4 h after terbutaline inhalation.
  
  
  RESULTS
  Baseline serum potassium levels were higher following prior treatment with E and S; P, 3.78 mmol/L (3.67 to 3.88); T + E, 3.93 mmol-1 (3.82 to 4.03); and T + S, 4.03 mmol/L (3.93 to 4.14) (p less than 0.05). Mean potassium concentrations over 4 h were also higher following prior treatment with E and S; T, 3.58 mmol/L (3.54 to 3.63); T + E, 3.68 mmol/L (3.64 to 3.72) (p less than 0.05); and T + S, 3.73 mmol/L (3.68 to 3.78) (p less than 0.01).
  
  
  CONCLUSIONS
  Enalapril and spironolactone protect against the fall in serum potassium over 4 h by elevating baseline potassium concentration. These potassium-sparing drugs, however, should not be used to prevent the hypokalemic and electrocardiographic sequelae of inhaled beta 2-agonists.
authors.affiliation: Department of Clinical Pharmacology, Ninewells Hospital and Medical School, Dundee, Scotland.
authors.forename: A R
authors.initials: AR
authors.lastname: Rahman
authors.forename: D G
authors.initials: DG
authors.lastname: McDevitt
authors.forename: A D
authors.initials: AD
authors.lastname: Struthers
authors.forename: B J
authors.initials: BJ
authors.lastname: Lipworth
mesh_terms: D000328:Adult; D004562:Electrocardiography / Q000187:drug effects; D004656:Enalapril / Q000627:therapeutic use*; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007008:Hypokalemia / Q000097:blood / Q000139:chemically induced / Q000517:prevention & control*; D008274:Magnesium / Q000097:blood; D008297:Male; D011188:Potassium / Q000097:blood; D012083:Renin / Q000097:blood; D016037:Single-Blind Method; D013148:Spironolactone / Q000627:therapeutic use*; D013726:Terbutaline / Q000037:antagonists & inhibitors*
chemical_list: D013148:Spironolactone; D004656:Enalapril; D012083:Renin; D008274:Magnesium; D013726:Terbutaline; D011188:Potassium