• dose–response;
  • inhalation;
  • urinary salbutamol

Aims  To determine the reproducibility and dose–response relationship for urinary salbutamol excretion post inhalation.

Methods  Fifteen volunteers inhaled either one, two, three, four or five doses of 100 µg salbutamol on separate days and then seven of these also repeated each of the one, three and five doses on five occasions. After each study dose urine was collected 30 min post inhalation.

Results  The mean (SD) 30 min urinary salbutamol after one, two, three, four and five doses was 2.61 (1.0.), 5.47 (1.59), 8.68 (2.73), 12.34 (3.96) and 15.99 (4.50) µg, respectively. Statistical analysis revealed a linear relationship (P < 0.001). Mean (SD) coefficient of variation after one, three and five doses was 10.5 (3.6), 10.1 (2.7) and 9.4 (2.3)%.

Conclusions  The 30 min salbutamol urinary excretion post inhalation pharmacokinetic method, to compare inhaled products, is linear with inhaled dose and reproducible.