Abstract

We aimed to assess the plasma and urine concentrations of β2-agonists and evaluate the difference between three routes of administration in trained adults in order to distinguish doping from prevention of exercise-induced asthma. Ten young healthy Caucasian male subjects received during a four treatment period study: 1) inhaled salbutamol (SI) 2 × 100 µg t.i.d. for 3 days, 2) inhaled formoterol (FI) 2 × 12 µg b.i.d. for 3 days, 3) a single subcutaneous injection of salbutamol (SS) 0.5 mg, and 4) salbutamol 2 × 2 mg t.i.d. orally for 3 days (SO). Blood samples were taken during the first and the third day of experimentation at baseline, 30 min, 1 h, 2 h, 4 h and 6 h after administration; additional blood samples were drawn at 15 min for SI, SS and FI and at 12 h for FI. Urinary samples were collected at baseline, 2 h, 4 h, 6 h and 12 h after administration. Urinary concentrations were 20 to almost 50 times higher after SO than after SI. Mean urinary concentration after SO increased to above 800 ng/mL within the two hours and above 1000 ng/mL at 6 to 12 hours post-drug administration. Urinary concentrations after SS were maximal during the first 2 hours (mean: 340 ± 172 ng/mL). Plasma concentrations were very low, whatever the routes of administration. Results showed that we could eliminate the use of SI (authorized) and SS administration when individual urinary concentrations are higher than 230 ng/mL and 615 ng/mL, respectively. Therefore, at rest, the cut-off value used to discriminate therapeutic from doping salbutamol intake could be fixed at 250 ng/mL instead of the 1000 ng/mL still authorized by international committees. Verf.-Referat