Developing greener and more effective inhalers

The challenge of developing more environmentally friendly inhalers has provided the perfect opportunity to improve current formulations of pharmaceutical aerosols.

Pharmaceutical aerosols play a crucial role in the health and well-being of millions of people throughout the world. These products include MDIs, which maintain quality of life and in some cases can sustain life.

Traditionally, MDIs have been propelled using chlorofluorocarbons (CFCs). Since these have been linked to stratospheric ozone depletion, they are now being redeveloped to contain non-ozone-depleting propellants. This presents an opportunity to improve today’s formulations and to create new systems to treat many infirmities and afflictions.

CFC alternatives

In medical applications CFC alternatives must satisfy more than just environmental requirements. The first consideration is the toxicity profile of the substitute. Also, for the sake of patient safety, they cannot be flammable. Finally, their physical properties must allow workable formulations within the available technology.

DuPont, one of the world’s most innovative science companies and two-time award winner of the United States National Medal of Technology, has developed two CFC replacement compounds. Both are pharmaceutical grade propellants with drug master files submitted worldwide. Dymel® 134a/P (HFA-134a) and Dymel 227ea/P (HFA-227ea) provide safe, non-flammable alternatives to CFCs, with the necessary physical properties.

HFA-134a closely resembles CFC-12, which was the most widely used pharmaceutical aerosol propellant. CFC-12 comprised about 65% of the total CFC market for the MDI application and a higher proportion of the total pharmaceutical aerosol market. HFA-134a is thermally and hydrolytically stable, and inert towards conventional solvents and active ingredients. Additionally, since it is a CFC replacement in other applications, such as refrigeration and plastic foams, it is widely available and economically acceptable for the pharmaceutical application.

HFA-227ea has similar properties to HFA-134a, but has a lower vapour pressure than HFA-134a. It is predominantly used in MDIs to lower the pressure of HFA-134a formulations, in much the same way that CFCs 11 and 114 were used to lower the pressure of CFC-12 formulations. These blends of Dymel 134a/P and Dymel 227ea/P can offer customers the flexibility of increased formulation options. Since blends can provide a range of pressures and liquid densities, they help to recover some of the flexibility that the market had with CFCs 11 and 12.

DuPont Dymel products are offered and sourced worldwide, and both 134a/P and 227ea/P are commercially used in pharmaceutical products.

In addition to the propellants, DuPont brings its unparalleled technical capabilities and support to the customer, providing not only expertise in fluorochemicals, but access to broader resources in other fields such as particle science technology, toxicity and pharmaceutical packaging.

Health benefits of pharmaceutical aerosols

Pharmaceutical aerosols will continue to play an important role in medicine. HFA-based MDIs will increase as the transition from CFCs proceeds.

Recent developments in respiratory drug delivery are good indicators of the future of inhaled drugs. The lung is currently seen as a likely route of delivery for systemic and even macromolecular drugs, which would broaden the classes of agents delivered via pharmaceutical aerosols. To help customers develop these and other new products, DuPont will continue to be the supplier of choice for pharmaceutical propellants.

Company profile

Founded in 1802, DuPont offers products and services to markets such as nutrition, agriculture, construction and transport. Visit: www.dupont.com/dymel.

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