Background: Urinary pharmacokinetic methods have been identified to determine the relative lung and systemic bioavailability after an inhalation. We have extended this methodology to inhaled beclometasone dipropionate (BDP).
Methods: Ethical approval was obtained and all subjects gave consent. Twelve healthy- volunteers received randomised doses, separated by >7 days, of 2000µg BDP solution with (OralC) and without (Oral) 5g oral charcoal, ten 100µg inhalations from a Qvar® Easibreathe metered dose inhaler (pMDI) with (QvarC) and without (Qvar) oral charcoal and eight 250µg inhalations from a Clenil® pMDI (Clenil). Subjects provided urine samples at 0, 0.5, 1, 2, 3, 5, 8, 12, and 24 hours post study dose.Urinary concentrations of BDP and its metabolites, beclometasone -17- monopropionate (BMP) and beclometasone (BOH) were measured.
Results: No BDP, BMP, or BOH was detected in any samples post OralC dosing. Post oral dosing no BDP was detected in all urine samples and no BMP or BOH was excreted in the first 30 minutes. Significantly more (p < 0.001) BDP, BMP and BOH was excreted in the first 30 minutes and cumulative 24 urinary excretions post Qvar and Clenil compared to Oral. Using 30 minute urinary excretion the mean ratio (90% confidence interval) for Qvar compared to Clenil was 231.4 (209.6, 255.7).
Conclusions: The urinary pharmacokinetic methodology to determine the relative lung and systemic bioavailability post inhalation, using 30 minute and pooled 24 hour post inhalation samples, applies to BDP. The ratio between Qvar and Clenil is consistent with related clinical and gamma scintigraphy lung deposition studies.
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)
