The purpose of the present study was to investigate pharmacokinetics of procaterol in asthmatics and non-asthmatics after nebulized and oral administration in relation to doping. Ten asthmatic and ten non-asthmatic subjects underwent two pharmacokinetic trials. At first trial, 4 μg procaterol was administered as nebulization. At second trial, 100 μg procaterol was administered orally. Serum and urine samples were collected before and after administration of procaterol. Samples were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Serum and urine concentrations of procaterol were markedly higher after oral administration compared to nebulized administration. After oral administration, serum procaterol concentration-time area under the curve (AUC) was higher (P ≤ 0.05) for asthmatics than non-asthmatics. Likewise, urine concentrations were higher (P ≤ 0.01) for asthmatics than non-asthmatics 4 (47 ± 1 2 vs. 28 ± 9 ng/mL) and 8 h (39 ± 9 vs. 15 ± 5 ng/mL) after oral administration. Detection of serum procaterol was difficult after nebulized administration with 38 samples (27%) below limit of quantification (LOQ) and only trends were observed. No differences were observed between asthmatics and non-asthmatics in the urine concentrations of
procaterol after nebulized administration. In summary, our data showed that asthmatics had higher urine concentrations of procaterol than non-asthmatics after oral administration of 100 μg, whereas no difference was observed between the groups after nebulized administration. For doping control purposes, our observations indicate that it is possible to differentiate therapeutic nebulized administration of procaterol from proh ib ited use of oral procaterol.