Urinary excretion of ephedrine after nasal application in healthy volunteers.
The urinary excretion of ephedrine after intranasal administration of the drug was studied in 8 healthy volunteers. Ephedrine (6 drops of a commercial 0.75% nasal ephedrine solution in each nasal cavity) was administered 4 times at intervals of 2 h (total amount applied equivalent to approximately 14 mg ephedrine), and urine was collected each hour for 10 h; the volunteers exercised on a bicycle ergometer at 50% of their VO2max for 2 h after the last ephedrine application. Ephedrine was detected in all urine samples. The urinary ephedrine concentration ranged from 0.9 to 16.5 micrograms mL-1; the number of urine samples with an ephedrine concentration exceeding 5 micrograms mL-1 ranged from 1/10 (volunteer 2) to 9/10 (volunteers 1 and 3). The mean percentage of dose recovered within 10 h was 33% (range 23-50%). There was a weak but significant negative correlation between urinary pH and amount of ephedrine in the urine; exercise did not consistently influence the urinary amount. These results illustrate the systemic availability of ephedrine upon intranasal administration and show that the therapeutic use of a nasal ephedrine formulation by an athlete on the day of a competition can lead to a urinary ephedrine concentration above 5 micrograms mL-1, which is considered positive in current doping regulations of the International Union of Cyclists.
Heymans Institute of Pharmacology, University of Gent Medical School, Belgium.
R A
RA
Lefebvre
F
F
Surmont
J
J
Bouckaert
E
E
Moerman
D000281:Administration, Intranasal; D000328:Adult; D004809:Ephedrine / Q000008:administration & dosage / Q000652:urine*; D015444:Exercise; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male
D004809:Ephedrine