Abstract

BACKGROUND--The 30 minute and 24 hour post-inhalation urinary excretion of salbutamol represents the relative amount of drug deposited in the lungs and total systemic absorption, respectively. Using this method two metered dose inhalers used with a Volumatic (Allen and Hanburys Ltd, UK) large volume spacer have been compared. METHOD--Eleven healthy volunteers inhaled 4 x 100 micrograms salbutamol from either a generic salbutamol (Baker Norton, UK) or Ventolin (Allen and Hanburys Ltd, UK) metered dose inhaler with a Volumatic. The order of administration was randomised with a seven day washout period. Urine samples were collected for 0-30 minutes and then pooled up to 24 hours after inhalation. RESULTS--The mean (SD) urinary salbutamol excretion 30 minutes after inhalation with the metered dose inhalers used with the Volumatic was 22.22 (4.63) and 21.30 (5.91) micrograms for the Baker Norton and Ventolin respectively, with a mean difference (95% confidence interval (CI)) of 0.92 (-0.65 to 2.49) micrograms. Similar amounts were excreted up to 24 hours after the dose with a mean (SD) urinary excretion of 116.1 (24.3) micrograms and 114.8 (22.3) micrograms, respectively, and a mean difference (95% CI) of 1.22 (-20.39 to 22.84) micrograms. CONCLUSION--Inhalations from generic salbutamol (Baker Norton) and Ventolin metered dose inhalers with a Volumatic inhalation aid deliver similar amounts of drug to the lungs and the total systemic absorption from the two products is the same.