Multidisciplinary Respiratory Medicine (Jun 2017)

Instant velocity and consistency of emitted cloud change by the different levels of canister filling with Metered Dose Inhalers (MDIs), but not with Soft Mist Inhalers (SMIs): a bench study

  • Roberto W. Dal Negro,
  • Pietro Longo,
  • Orestepaolo Villanis Ziani,
  • Luca Bonadiman,
  • Paola Turco

DOI
https://doi.org/10.1186/s40248-017-0096-1
Journal volume & issue
Vol. 12, no. 1
pp. 1 – 6

Abstract

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Abstract Background Inhalation is the preferred route for respiratory drug delivery, but several factors contribute to the variability of the respirable dose fraction. Instant velocity and the dynamic characteristics of the droplet cloud represent crucial factors. Aim was to measure and compare the instant velocity and the consistency of emitted cloud from five different MDIs (A - Salbutamol sulphate 100mcg, GSK; B - Salbutamol sulphate 100mcg, Valeas; C - Salmeterol xinafoate/Fluticasone propionate 25/125mcg, GSK; D - Formoterol fumarate/Bechlomethasone propionate 6/100mcg, Chiesi; E - Formoterol fumarate/Fluticasone dipropionate 5/125mcg, Mundipharma) and one SMI (Tiotropium bromide 5mcg, Boehringer Ingelheim), at different distance from the nozzle and canister filling. Methods Measurements were made at 90, 50, and 10% of canister filling, and at 5, 10, and 20 cm from the nozzle, for a total of 972 puffs. A high speed video photography protocol was adopted and high speed cameras (1.200 frames/sec.) were used. Data were acquired by means of specialized softwares. Temperature, humidity, and vibrations occurrence were strictly controlled during measurements. Statistics: Anova and p 33% at 90% of emptying with all other MDIs (p < 0–037; p < 0.001; p < 0.005, and p < 0.001, respectively). Instant velocity was extremely lower (p < 0.001) and constant for all levels of canister filling (p = ns) with SMI. All MDIs had a very fast jet phase, ranging 0.01–0.03 s at 10 cm, and 0.03–0.05 s at 20 cm from the nozzle, without any significant difference from each other (p = ns). MDIs generated a cloud similarly tight (p = ns) at 10 and 20 cm from the nozzle, while it was extremely wider and constant with the SMI (p = 0–001). Also the cloud turbulence was minimized during the SMI emission. Discussion and Conclusions MDIs are characterized by a substantial variability in both their instant velocity and consistency of the emitted cloud at different levels of canister filling. SMI generates a much slower soft mist cloud which is constantly homogeneous and independent of canister emptying. These peculiarities assessed at bench are suggesting a higher dose consistency and a much more effective therapeutic performance also in real life.

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