Aerosols in the Health Care Field

:: Section 3

CFC and HFA

Although CFC was a commonly used propellent, in recent years it has been gradually replaced by HFA. The replacement of reegineered MDI with HFA propellent has actually demonstrated better preformance than the traditional CFC models, in particular in lung deposition of the aerosol drug. For example, the HFA-propelled MDI formulation of beclomethasone dispropionate (BDP; a corticosteroid) has increased more than five times of the traditional amount of 10% for lung deposition by the CFC devices. The following figures illustrate a comparison of lung delivery between CFC-based and HFA-based MDI systems.

(Figures are courtesey of Dr. Yung Sung Cheng, Lovelace Respiratory Research Institute)

Disadvantages of CFC and HFA

Disadvantages of CFC include:

1. Some patients have shown adverse reponses with Freon.

2. Because the CFCs have adverse effects on global warming and stratospheric ozone destruction, the use of CFCs has been banned in many countries.

Disadvantages of HFA

1. Because of the different properties, the plume geometries of HFA based formulation used in devices designed for CFC are not the same as designed. For example, when HFA-based albuterol (Proventil HFA) is used in a universal adapter designed for CFC albuterol, the MMAD and GSD increase significantly. The result is that significantly less drug is available to the patient.

1. Is a HFA-based MDI system better than a CFC-based system?