The Science Journal of the American Association for Respiratory Care

2005 OPEN FORUM Abstracts

In vitro evaluation of drug particle size delivered fromMDIs with a breath-actuation device.

Robert A. Casper, Ph.D., Chief Technical Officer, Respirics Inc., Raleigh, NC.

Background
: Metered dose inhalers continue to be widely used by patients despite reported difficulties with their use. We evaluated the use of different MDIs in conjunction with various technologies designed to assist with the delivery of aerosolized medications. We compared the mass median aerodynamic diameter (MMAD) of drug delivered from three separate MDIs when used alone, with a valved holding chamber (PocketSpacerT) and with MD TurboT, a breath-actuation device.

Methods
: Three different MDIs (albuterol, metaproterenol and fluticasone) were tested by attachment to a throat model, feeding into an Anderson 8-stage cascade impactor. Airflow through the impactor was regulated at a constant rate of 28.3 L/min. Each MDI was tested (n=10 actuations) alone, with a valved holding chamber and then with MD Turbo. Active drug collected on the 8 plates was assayed by HPLC.

Results
: The results show that the particle size distribution (MMAD) of drug delivered from the MDI with the assistance of the MD Turbo is comparable to the MMAD of drug from both delivery using the inhaler on its own or delivery with the aid of a valved holding chamber.

Conclusions
: We conclude that the MD Turbo can be used with a variety of MDIs to assist with delivery of aerosolized medications.

Particle Size Delivered

  MDI + MD Turbo MDI + Pocket Spacer MDI Alone
  MMAD (mg ±SD) GSD MMAD (mg ±SD) GSD MMAD (mg ±SD) GSD
Albuterol 1.75±0.06 1.68±0.2 1.73±0.02 1.51±0.01 1.80±0.04 1.57±0.01
Metaproterenol sulfate 4.80±0.17 1.75±0.05 4.19±0.08 1.68±0.05 4.64±0.19 1.75±0.03
Fluticasone propionate 2.31±0.28 1.69±0.11 2.29±0.25 1.65±0.06 2.26±0.22 1.66±0.06
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