Urine Concentrations of Vilanterol After Inhaled Administration of Vilanterol/Fluticasone Furoate

Introduction: The prevalence of asthma and exercise-induced bronchoconstriction is high in the athletic population. In endurance sport, the prevalence has been reported to be as high as 30-50% compared to the general population prevalence of approximately 5-10% in Western countries. First-line treatment in asthma is reliever medication and inhaled corticosteroids (ICS). Therefore, β2-adrenoceptor agonists and ICS are commonly prescribed drugs to athletes. Although long-acting β2-agonists (LABA) are the most commonly used β2-agonists in asthma management, development of ultra-long acting β2-agonists (U-LABA) as vilanterol may change this. U-LABA has a long duration of action (24 hours) compared with LABA (12 hours). The accumulated number of inhalations per day for elite athletes may thus be reduced when prescribed with U-LABA as compared to LABA. Use of β2-agonists are restricted by the World Anti-Doping Agency (WADA). As of 2018, β2-agonists salbutamol, formoterol and salmeterol are allowed by inhalation in therapeutic doses, whereas other β2-agonists, such as terbutaline and vilanterol still require the athlete to obtain a therapeutic use exemption (TUE). To discriminate therapeutic use from supra-therapeutic misuse, WADA has established urinary thresholds and decision limits based on urine concentrations of salbutamol, salmeterol and formoterol. However, while data on urine concentrations of these three β2-agonists are well-described in studies that simulate sport-specific situations that are applicable for doping control, no such data exist for the novel U-LABA vilanterol. For instance, asthmatic athletes using β2-agonists usually inhale the drug before training or competition as prophylaxis for bronchoconstriction. Thus, studies are needed to investigate the urine concentrations of vilanterol after inhaled administration in set-ups that are applicable to doping control which this study aims to investigate. Method: The study is divided in two phases. The first