Ventolin Diskus and Inspyril Turbuhaler: an in vitro comparison.

Dose delivery (total emitted dose, or TED) from dry powder inhalers (DPIs), pulmonary deposition, and the biological effects depend on drug formulation and device and patient characteristics. The aim of this study was to measure, in vitro, the relationship between parameters of inhalation profiles recorded from patients, the TED and fine particle mass (FPM) of Diskus and Turbuhaler inhalers. Inhalation profiles (IPs) of 25 patients, a representative sample of a wide range of 1500 IPs generated by 10 stable asthmatics, 3 x 16 (mild/moderate/severe) COPD patients and 15 hospitalized patients with an exacerbation asthma or COPD, were selected for each device. These 25 IPs were input IPs for the Electronic Lung (a computerdriven inhalation simulator) to determine particle size distribution from Ventolin Diskus and Inspyril Turbuhaler. The TED and FPM of Diskus and FPM of Turbuhaler were affected by the peak inspiratory flow (PIF) and not by slope of the pressure-time curve, inhaled volume and inhalation time. This flow-dependency was more marked at lower flows (PIF < 40 L/min). Both the TED and FPM of Diskus were significantly higher as compared to those of the Turbuhaler [mean (SD) TED(_diskus) (%label claim) 83.5 (13.9) vs. TED(_turbuhaler) (72.5 (11.1) (p = 0.004), FPM(_diskus) (%label claim) 36.8 (9.8) vs FPM(_turbuhaler) (28.7 (7.7) (p < 0.05)]. The TED and FPM of Diskus and FPM of Turbuhaler were affected by PIF, the flow-dependency being greater at PIF values below 40 L/min. Lower PIFs occurred more often when using Turbuhaler than Diskus, since Turbuhaler have a higher resistivity, requires substantially higher pressure in order to generate the same flow as Diskus. TED, dose consistency and the FPM were higher for Diskus as compared to Turbuhaler. The flow dependency of TED and FPM was substantially influenced by inhalation profiles when not only profiles of the usual outpatient population were included but also the real outliers from exacerbated patients.

Ex-vivo product performance of Diskus and Turbuhaler inhalers using inhalation profiles from patients with severe chronic obstructive pulmonary disease.

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.

Fine particle mass from the Diskus inhaler and Turbuhaler inhaler in children with asthma.

The study aimed to investigate dose consistency and particle distribution from the dry powder inhalers Diskus and Turbuhaler. Full profiles of inhalation pressure versus time were recorded in 18 4 yr old and 18 8 yr old asthmatic children through Diskus and Turbuhaler inhalers. These data were used in an inhalation profile simulator to assess drug delivery from both a Diskus inhaler and a Turbuhaler inhaler, and in particular to assess the proportion of drug emitted in the coarse (>4.7 microm) and fine (<4.7 microm) particle size range from each type of inhaler. The inhalation profile more accurately represents the changes in flow rate over time through the device than the constant flow rate usually applied with an impactor alone. The aerosol cloud was released before the peak inspiratory effort had been achieved and accordingly the early part and not the peak of the inspiratory performance is a determinant of the quality of the aerosol. The mean (SD) amount of drug in large particles (>4.7 microm), fine particles (<4.7 microm) and very fine particles (<2.1 microm) in percentage of label claim from the Fluticasone Diskus was 72 (5), 15 (2) and 2 (1) from the 4 yr old children and 71 (3), 18 (2) and 2 (1) from the 8 yr old children, respectively. Similar particle fractions from the Budesonide Turbuhaler were 35 (9), 21 (10) and 7 (5) from 4 yr old children and 30 (7), 32 (9) and 12 (6) from 8 yr old children. In conclusion, the Diskus inhaler provides an improved dose consistency through the varying age groups and inspiratory flow performances when compared to the Turbuhaler in terms of the proportion of the dose emitted at each particle size. This improvement is at the expense of a low fine particle mass and a high proportion of coarse particles from the Diskus as compared with the Turbuhaler.