Blood and Urinary Concentrations of Salbutamol in Asthmatic Subjects

Abstract

Median urinary concentrations after oral administration of 8 mg of salbutamol were significantly higher than those after inhalation of 0.8 mg of salbutamol.

The influence of exercise and dehydration on the urine concentrations of salbutamol after inhaled administration of 1600 µg salbutamol as a single dose in relation to doping analysis

“…[25,26] Such large shifts in the water content can result in concentrated plasma and explain the larger concentrations of salbutamol found in serum during exercise. [25,26] Nevertheless, given the large inter-individual difference in the serum concentrations of salbutamol observed in the present and previous studies after oral and inhaled administration, [9,17,18,21] it does not appear that blood samples are suitable for doping control purposes in cases of salbutamol. While studies suggest that exercise compromises glomerular filtration rate and renal excretion, [27][28][29][30] we observed no effect of EX on glomerular filtration rate and amount of salbutamol excreted in the urine compared to R. This discrepancy may be related to the exercise intensity.…”

Urine concentrations of oral salbutamol in samples collected after intense exercise in endurance athletes

“…[7] Urine concentrations of salbutamol in the present study, revealed concentrations similar with those from non-athletic subjects collected in resting conditions. [10,12] This finding is important since several mechanisms related to exercise might influence urine concentrations of salbutamol. Exercise might compromise glomerular filtration rate and osmotic clearance, [21][22][23] thus decreasing urine excretion of salbutamol.…”

“…Although former studies have investigated urine concentrations of salbutamol after oral administration, [6,8,10,12] few have investigated concentrations after exercise in athletes. [7] Urine concentrations of salbutamol in the present study, revealed concentrations similar with those from non-athletic subjects collected in resting conditions.…”

“…Pharmacokinetic studies of inhaled and oral salbutamol have been conducted to support the urinary threshold. [6][7][8][9][10][11][12][13] Most of these studies, however, have investigated urine concentrations of salbutamol in resting conditions in non-athletic subjects, and not after exercise in athletes. Doping testing is often performed after a training session or a competitive event, and elite athletes usually take their beta 2 -agonists prior to training or competition.…”

“…[10,[13][14][15] Furthermore, a large number of urine samples collected after oral administration of salbutamol reveal concentrations below the current decision limit of 1200 ng/mL when unadjusted for USG. [10,12] Currently, WADA regulations do not require laboratories to adjust urine samples of beta 2 -agonists for USG. [16] Urine samples of beta 2 -agonists that are unadjusted for USG could potentially give false negative doping test results, especially in samples with low USG, even after prohibited oral administration of salbutamol.…”