Dosing performance of dry powder inhalers is dependent on patient's inspiratory effort. This study compares the inhalation profiles generated by patients with severe obstructive lung disease using Diskus and Turbuhaler inhalers. The patient profiles are subsequently used to determine the dosing performance of fluticasone propionate Diskus and budesonide Turbuhaler inhalers. Inhalation profiles were recorded in COPD patients (FEV1 < or = 30% predicted) as they inhaled with maximal effort through the inhalers. The profiles were used in an inhalation simulator to assess the dosing performance by measuring the total emitted dose and the fine particle mass for each inhaler type. Peak inspiratory flow was significantly higher through the Diskus (mean 82.31 min(-1)) compared with Turbuhaler (mean 53.51 min(-1), difference = 28.8 l min(-1); P < 0.0001). In addition, in direct comparison of the two devices. the Diskus was shown to deliver a more consistent dose irrespective of flow than the Turbuhaler in this patient population. These findings may be of importance in optimising selection of devices for patients with severe airway obstruction.
Abstractbronchodilatation, 1 reduction in diurnal variation in peak expiratory flow, improvement in Background -Salbutamol is the most widely prescribed short acting 2 agonist daytime and nocturnal symptoms, reduction in requirement for a short acting bronchodilator, 2 3and salmeterol is the first long acting inhaled 2 agonist. The dose equivalence of and increased quality of life 4 in asthmatic patients. Bronchodilatation 5 6 and protection salmeterol and salbutamol is disputed. Estimates of weight-for-weight dose ratio against non-specific bronchial challenge with histamine 7 or methacholine 8 are maintained for have ranged from 1:2 to 1:16. A study was undertaken to clarify the true dose ratio.at least 12 hours after a single dose of salmeterol compared with 4-6 hours after salbutamol. Methods -The bronchoprotection afforded against repeated methacholine chalSalmeterol and salbutamol have similar 2 receptor selectivity 9 but dose equivalence is lenge by inhaled salmeterol 25 g and 100 g and salbutamol 100 g and 400 g disputed, estimates of the weight-for-weight dose ratio ranging from 1:2 to 1:16 in single was compared in a randomised, double blind, placebo controlled, crossover trial. dose studies.5 7 10 11 In the light of continuing debate regarding a possible association between Subjects were 16 stable asthmatics with a baseline forced expiratory volume in one the use of 2 agonists and increasing asthma morbidity and mortality worldwide and consecond (FEV 1 ) of [65% predicted, screening concentration provoking a fall in FEV 1 cern about relative potencies of different agents, 12 it is important that the relative poof 20% (PC 20 FEV 1 ) of Ζ8 mg/ml, and a shift in PC 20 FEV 1 of more than two doubling tencies of these two drugs be defined.Increased responsiveness to non-specific concentration steps following inhalation of salbutamol 400 g. On five separate oc-bronchoconstrictor agents is a characteristic feature of clinical asthma 13 and inhaled hiscasions subjects underwent methacholine challenge before and 30 and 120 minutes tamine or methacholine bronchoprovocation tests are commonly used in diagnosis in patients after drug administration. PD 20 FEV 1 was calculated for each challenge. FEV 1 at 90 who present with vague or atypical symptoms.
14The aim of this placebo controlled study was minutes after drug administration was also recorded.to compare the potency of salmeterol and salbutamol in asthmatic subjects by measurement Results -Bronchoprotection afforded by salmeterol was increased at 120 minutes of the protection afforded by salmeterol 25 g and 100 g and salbutamol 100 g and 400 g compared with 30 minutes and protection by salbutamol was decreased. Protection against repeated methacholine challenge. The
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