Sunday, July 14, 2013

Bidding a Final Goodbye to Asthma Inhalers That Use CFCs as Propellants

As an asthma sufferer, you may find yourself with dual loyalties.  On the one hand, you want to protect the environment for your own health and for the sake of future generations inhabiting this planet.  On the other hand, you want to maintain good asthma control so that you can breathe.  Although there shouldn't be any conflict between these two goals, you may have sensed that there has been ever since pharmaceutical manufacturers started eliminating asthma medications using chlorofluorocarbons (CFCs) to propel the mist from your inhalers.  CFCs are harmful to the environment.  Together with similar molecules formerly used in refrigeration and air conditioning, CFCs interact with gases high in the atmosphere above us, depleting ozone from the stratosphere.  Enlarging ozone holes in the atmosphere and the role of CFCs in causing their formation were discovered by scientists in the 1980s, and by 1989 countries around the world agreed to stop manufacture and sale of most CFCs.  Slowly we have seen elimination of CFCs as propellants for our metered-dose inhalers.

First came albuterol.  Albuterol-CFC was replaced by albuterol-HFA, which used an environmentally-safer propellant called hydrofluoroalkane.  Initially, one pharmaceutical company released its albuterol-HFA inhaler, then came others.  We now have three: ProAir-HFA, Proventil-HFA, and Ventolin-HFA.  It was not a happy transition.  Because there is no generic albuterol-HFA, the cost of these quick-relief medications jumped dramatically.  There was the widespread perception that the new inhalers did not work as well as the old albuterol-CFC inhalers, although careful scientific comparisons between the old and new could find no differences.  And finally, the new medication has a tendency to stick where the metal canister sits in plastic holder, clogging the mechanism and requiring periodic cleaning of the device so that the medication is released freely.

Since then, other asthma medications have been released as metered-dose inhalers with HFA propellants, including the steroids beclomethasone (formerly Beclovent and Vanceril) as Qvar-HFA, fluticasone as Flovent-HFA, and newest among them, ciclesonide, as Alvesco-HFA.  However, not all medications made the transition to the new propellant.  The inhaled steroids, triamcinolone (Azmacort) and flunisolide (Aerobid), simply disappeared from the market, as did the once widely used anti-inflammatory medication, cromolyn (Intal).  Other manufacturers released their asthma medications not as metered-dose inhalers at all but in a dry-powder formulation.  The inhaled steroids budesonide (Pulmicort), fluticasone (Flovent), and mometasone (Asmanex) are available as multi-dose dry-powder inhalers.

This summer marks the end of the road for CFC-driven inhalers.  The last two are both quick-acting bronchodilators -- albuterol plus ipratropium in the Combivent inhaler (more often used to treat COPD than asthma) and pirbuterol in the Maxair Autohaler.  Maxair will simply be withdrawn from the market; Combivent is being released using a novel delivery system, called a "soft mist" inhaler (Combivent Respimat).  This latter new system is a tribute to the inventiveness of pharmaceutical manufacturers as they work to make inhaled medications available in ways that are both effective and safe for our environment. 

The silver lining in all of this is that globally the amount of CFC-type chemicals in the atmosphere decreased by approximately 10% between 1994 and 2008.  It is predicted that the ozone hole over the Antarctic will decrease in size by 2015 and may completely recover by 2050.  We care about the protective ozone layer in our planet's atmosphere because its depletion is associated with increased exposure to ultraviolet light (UVB) on the planet's surface, increasing our risk of skin cancers and cataracts and potentially causing damage to crops and sea life.  With the help of scientific expertise, global cooperation, and some flexibility on our parts, it may be possible to "have our cake and eat it too," or in this case, to protect "spaceship earth" and breathe freely too.