Salbutamol (INN) or albuterol (USAN) is a short-acting β2-adrenergic receptor agonist used for the relief of bronchospasm in conditions such as asthma and chronic obstructive pulmonary disease. It is marketed by GlaxoSmithKline as Ventolin or Ventorlin depending on the market; by Cipla as Asthalin; by Schering-Plough as Proventil and by Teva as ProAir. Many other generic trade names also exist.
Salbutamol sulfate is usually given by the inhaled route for direct effect on bronchial smooth muscle. This is usually achieved through a metered dose inhaler (MDI), nebuliser or other proprietary delivery devices (e.g. Rotahaler or Autohaler). In these forms of delivery, the maximal effect of Salbutamol can take place within five to twenty minutes of dosing, though some relief is immediately seen. Salbutamol can also be given orally as an inhalant or intravenously. However, some asthmatics do not have the required DNA base sequence in a specific gene and may not respond to these medications.
As a β2-agonist, salbutamol also finds use in obstetrics. Intravenous salbutamol can be used as a tocolytic to relax the uterine smooth muscle to delay premature labour. While preferred over agents such as atosiban and ritodrine, its role has largely been replaced by the calcium-channel blocker nifedipine which is more effective, better tolerated and orally administered.
The U.S. Food & Drug Administration in April of 2005 mandated that all (including albuterol) inhalers containing chlorofluorocarbons (CFCs) will be prohibited in the United States as of 12/31/2008. CFC inhalers had previously been given "essential use" status, exempting it from a CFC-production ban, however in accordance with the Montreal Protocol they will be phased out; in many other countries patients have been transitioned to non-CFC based inhalers using hydrofluoroalkane (HFA) propellant. Pharmaceutical manufacturers are expected to produce adequate supplies of alternative (HFA) inhalers by 2009.
One drawback of this transition to HFA inhalers is that due to patent restrictions all of the HFA albuterol inhalers are "brand-name" (ProAir, Proventil, and Ventolin). They cost approximately $20 more per inhaler than existing generic CFC albuterol inhalers. Three of the four available albuterol/levalbuterol HFA inhalers on the market also contain 10-14% ethanol by weight. Ventolin HFA is the exception.
For reference, ethanol is a known bronchoconstrictor.
Generic HFA albuterol inhalers are not expected on the market until 2017 due to existing patents, although some pharmaceutical companies will offer discounts for those who cannot afford the HFA inhalers.
Another drawback that is coming to light now as the use of HFA/HFA+ethanol inhalers is expanding seems to be a far higher intolerance of the new inhalers compared to CFC propellant in patients. Registered complaints run the gamut from "doesn't seem to work as well" all the way to serious anaphylaxis in response to using an HFA or HFA+ethanol inhaler.
Albuterol is widely used, and accounts for anywhere from 78% of all bronchodilator prescriptions in 2005 to 85% in 2008. However, patients in the United States who cannot tolerate the HFA albuterol inhalers will not have a single albuterol alternative available to them domestically after December 31, 2008. The FDA did not approve any alternatives to HFA and there are few standard inhaled lung medications in the United States that come in Dry Powder Inhaler (DPI) versions. Noticibly missing is albuterol in DPI form in the United States, although it is available in most of the rest of the world in salbutamol DPIs.
The benefits of transitioning to HFA inhalers include (1) increased drug deposition in the distal airways, (2) more consistent drug delivery from nearly empty canisters, and (3) more consistent drug delivery at a greater range of canister temperatures. It should be noted that the spray force of HFA inhalers is less than that of CFC inhalers, which may mislead some patients to believe that they may not be receiving enough albuterol when in fact they are seeing the benefits as outlined above.
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