HFC usage is limited to products where health and safety during use requires a non-flammable and virtually non-toxic propellant.Medical aerosol applications have these requirements, which was provided traditionnaly by the CFCs, progressively replaced by HCFs, the only propellants that can meet the need of non-flammability, while being virtually non-toxic.
These aerosol products are extremely important e.g. Metered Dose Inhalers (MDIs) for therapy of asthma and other respiratory problems. MDIs prove to be a very effective means of administering the active drug, are cost effective and particularly suitable for use by children and the elderly. Propellants of proven very low toxicity must be used for this application.
Medical aerosols are essential for patients health, and as much must be distinguishead from industrial aerosols.
The HFCs 134a and 227ea (both pharma grade) are used as propellants for metered dose inhalers (MDIs) for the treatment of asthma and chronic obstructive pulmonary diseases (COPD).
There is international consensus that primary treatment of these diseases should be via inhalation, with the MDI remaining the dominant inhaled delivery system in most countries and for all categories of drugs.
The incidence of asthma and COPD in developed countries is around 5 to 8 % of the population and increasing at an average rate of around 5 % per year.
These diseases are particularly prevelant amongst children, as the incidence in this group now approaches 15 % in Western Europe.
Worldwide at least 300 million people suffer from asthma, and a comparable number from COPD. A minimum of 50 to 60 million patients therefore rely on metered dose inhalers.