Relative bioavailability of salbutamol to the lung following inhalation via a novel dry powder inhaler and a standard metered dose inhaler.
OBJECTIVE
The number of dry powder inhaler (DPI) devices could increase because they are easier to use than a metered dose inhaler (MDI). Using urinary excretion, the relative bioavailability of salbutamol to the lungs and the body for a prototype DPI has been compared with an MDI.


METHODS
A randomized, double-blind, two way crossover study compared the amount of salbutamol in the urine 30 min following inhalation of 2 x 100 micrograms salbutamol from a prototype DPI (Innovata Biomed Ltd, UK) and a Ventolin (Allen and Hanburys Ltd, UK) MDI in 10 volunteers. The amount of salbutamol and its metabolite, the ester sulphate conjugate, renally excreted up to 24 h post inhalation was also determined to evaluate the relative bioavailability of salbutamol to the body.


RESULTS
The mean (s.d.) 30 min post-treatment urinary excretion for the prototype DPI and MDI was 8.4 (2.6) and 5.0 (1.9) micrograms, respectively (P < 0.001). The total amount of salbutamol and its ester metabolite excreted in the urine over the 24 h period after inhalation was 187.9 (77.6) and 137.6 (40.0) micrograms (P < 0.05).


CONCLUSIONS
The prototype DPI delivered more salbutamol to the body and the lungs than a conventional MDI. This finding supports further development of the prototype DPI. The urinary salbutamol method is able to discriminate between two different inhalation systems.
Hindle
M
M
Pharmacy Practice, School of Pharmacy, University of Bradford, Bradford, UK.
Peers
E M
EM
Parry-Billings
M
M
Chrystyn
H
H
D000280:Administration, Inhalation; D000328:Adult; D000420:Albuterol / Q000008:administration & dosage / Q000493:pharmacokinetics*; D000704:Analysis of Variance; D001682:Biological Availability; D001993:Bronchodilator Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*; D002626:Chemistry, Pharmaceutical; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008168:Lung / Q000378:metabolism*; D008297:Male
D001993:Bronchodilator Agents; D000420:Albuterol