Comparison of bronchodilatory properties of transdermal and inhaled long-acting beta(2)-agonists

Background: Regular use of long-acting bronchodilators is recommended for symptomatic COPD patients. A transdermal type of beta(2)-agonist, tulobuterol, was recently developed. This agent shows the pharmacokinetic property Of a Sustained serum concentration for 24h. However, little has been reported about the bronchodilatory properties of this agent. Objectives: The aim of the present study was to compare the bronchodilatory action of transdermal beta(2)-agonist tulobuterol with that of inhaled long-acting beta(2)-agonist salmeterol. Methods: An open-label. randomized crossover study was performed. Eleven patients with stable COPD were enrolled in the study. Tulobuterol (2mg/day) or salmeterol (50 mu g, twice daily) was administered in a randomized, crossover manner. Forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and inspiratory capacity (IC) were measured before administration, every 2 It from 12 to 24h. and at 36h after the initial administration. Results: Transdermal beta(2)-agonist tulobuterol showed an improvement in FEV1, FVC and IC after dosing compared with those at baseline. Salmeterol also improved all parameters of FEV1, FVC and IC, and showed a greater improvement compared with the transdermal beta(2)-agonist tulobuterol (p<0.05). The values of the area under the curve (AUC) of FEV1, FVC and IC during the administration of tulobuterol were 2.98 +/- 1.05, 1.81 +/- 0.98 0.75 +/- 0.85Lh, respectively, and during the administration of salmeterol they were 6.39 +/- 1.12, 6.61 +/- 1.34, 4.28 +/- 0.91 L h, respectively. Conclusion: The transdermal beta(2)-agonist tulobuterol showed bronchodilatory action for at least 24 h by once daily administration. However. its bronchodilatory potency was about three times less than that of the inhaled beta(2)-agonist salmeterol. (C) 2007 Elsevier Ltd. All rights reserved.