The Pharmacokinetic Profile of Inhaled and Oral Salbutamol in Elite Athletes With Asthma and Nonasthmatic Subjects

Objective: Data on pharmacokinetics of inhaled and oral salbutamol in elite athletes with asthma are needed to differentiate between therapeutic use and doping in doping control. Design: An interventional open-label crossover. Setting: Respiratory Research Unit, Copenhagen University Hospital, Bispebjerg. Participants: Eight elite athletes with asthma and 10 nonasthmatic subjects aged 18 to 33 years. Intervention: Administration of 0.8 mg of inhaled salbutamol and 8 mg of oral salbutamol separated by 14 days. Main Outcome Measures: Urine concentration of free salbutamol. Results: Maximum urine concentrations peaked in the period of 0 to 4 hours after the administration of inhaled and oral salbutamol in both groups. Median concentrations after inhaled salbutamol and oral salbutamol were 401.6 and 2108.1 ng/mL in healthy subjects and 334.9 and 2975.2 ng/mL in elite athletes with asthma. There were no significant statistical differences between the groups. One sample exceeded the World Anti-Doping Agency threshold value of 1000 ng/mL with a urinary salbutamol concentration of 1057 ng/mL 4 hours after inhalation, when no correction for urine specific gravity was done. When this sample was corrected for urine specific gravity, the result was 661 ng/mL. Conclusions: We found no significant difference in pharmacokinetic profile of inhaled and oral salbutamol between elite athletes with asthma and nonasthmatic subjects. Our results indicate that urine salbutamol concentrations should be corrected for urine specific gravity when evaluating doping cases.