Aerosols in the Health Care Field

Although ideally it is desired to use 100% of the drug, aerosol devices only traditionally used in respiratory care deliver approximately 10% to 15% of the total drug dose to the lung. It can be lost to the mouth, stomach, apparatus and through exhalation. The pattern of loss differs among the types of devices. The MDI and the SVN show the greatest contrast in the loss pattern of aerosol drug;

• Most of the loss with an MDI occurs in the mouth and stomach (~80%).
• Most of the loss with an SVN is in the delivery apparatus (66%), with most of that remaining in the nebulizer, whereas an MDI loses approximately 10% in the actuator.
• The DPI is similar to the MDI in its pattern of aerosol loss.

Lung deposition and clinical response (Forced respiratory volume) for three bronchodilator (MDI, DPI, and gas-powered SVN) (Zainudin BMZ and others, 1990) are shown in the figure below. The percentage of lung deposition are 11.2%, 9.1%, and 9.9% for the MDI, DPI and SVN, respectively. The clinical response, measured by the improvement in FEV1 (Forced Expiratory Volume in 1 second), is also similar. These results support the view that the amount of aerosol drug, albuterol (400 µg), delivered to the lung is similar with any of the three device types. Furthermore, the clinical response is similar.

(The data are from Zainudin BMZ et al. (1990))

In the following sections, we will be exploring each type of generator.

What's the difference in loss pattern between a MDI and a SVN? Is the amount of aerosol drug delivered to the lung similar or different among the various types of aerosol generators?

Reference

Zainudin BMZ and others: Comparison of bronchodilator responses and deposition patterns of salbutamol inhaled from a pressurized metered dose inhaler, as a dry powder, and as a nebulae solution, Thorax 45: 469, 1990.