General Information

Ventolin HFA has been approved for the treatment or prevention of bronchospasm in adults and children four years of age and older with reversible obstructive airway disease, and for the prevention of exercise-induced bronchospasm in patients four years of age and older. Ventolin HFA is a new version of the Ventolin metered-dose inhaler (MDI) currently marketed by GlaxoSmithKline. However unlike the current version, the new inhaler does not use chlorofluorocarbons (CFCs) to propel the medication. Ventolin HFA uses an alternative propellant called HFA or hydrofluoroalkane.

CFCs have been implicated in the depletion of the ozone layer, and as a result, the use of CFC-aerosol products in the United States has been sharply curtailed over the last few decades. While CFC production and importation have been banned for all commercial purposes in the United States since 1996, an exception is made for medical products that are considered essential with no suitable alternatives. While no action to remove the albuterol CFC MDIs from the market is planned at this time, the approval of Ventolin HFA provides an additional albuterol HFA MDI option to patients and physicians.

Clinical Results

A 12-week, randomized, double-blind trial compared Ventolin HFA to CFC 11/12-propelled albuterol and an HFA-134a placebo inhaler. The trial included adolescent and adult subjects (12-76 years of age) with mild to moderate asthma. Serial forced expiratory volume in one second (FEV1) measurements showed that two inhalations of Ventolin HFA produced a significantly greater improvement in FEV1 over the pretreatment value than placebo.

A second 12-week, randomized, double-blind trial evaluated the effectiveness of switching subjects from CFC 11/12-propelled albuterol to Ventolin HFA. In an initial run-in phase, all subjects received CFC 11/12-propelled albuterol. During the double-blind treatment phase, Ventolin HFA was compared to CFC 11/12-propelled albuterol and an HFA-134a placebo inhaler in adolescent and adult subjects with mild to moderate asthma. Serial FEV1 measurements showed that two inhalations of Ventolin HFA produced significantly greater improvement in pulmonary function than placebo. The switching from CFC 11/12-propelled albuterol inhaler to Ventolin HFA did not reveal any clinically significant changes in the efficacy profile.

Additionally, a two-week, randomized, double-blind trial was conducted to compare Ventolin HFA, CFC 11/12-propelled albuterol, and an HFA-134a placebo inhaler in 135 pediatric subjects (4-11 years old) with mild to moderate asthma. Serial pulmonary function measurements showed that two inhalations of Ventolin HFA produced significantly greater improvement in pulmonary function than placebo, and that there were no significant differences between the groups treated with Ventolin HFA and CFC 11/12-propelled albuterol.

A controlled trial in adult subjects with asthma showed that two inhalations of Ventolin HFA taken approximately 30 minutes prior to exercise significantly prevented exercise-induced bronchospasm compared to an HFA-134a placebo inhaler. In addition, Ventolin HFA was shown to be clinically comparable to a CFC 11/12-propelled albuterol inhaler for this indication. (from Ventolin HFA Product Information)

Side Effects

Adverse events reported from clinical trials include (but are not limited to) the following:

Throat irritation

Upper respiratory inflammation

Viral respiratory infections

Cough

Musculoskeletal pain

Overall, the adverse events were similar between Ventolin HFA and a CFC 11/12-propelled albuterol inhaler. Additionally, according to the results of a two-week pediatric trial, the pediatric adverse event profile was generally similar to that of the adult.

Mechanism of Action

In vitro studies and in vivo pharmacologic studies have demonstrated that albuterol has a preferential effect on beta₂-adrenergic receptors compared to isoproterenol. Activation of beta₂-adrenergic receptors on airway smooth muscle leads to the activation of adenylcyclase, and to an increase in the intracellular concentration of cyclic-3',5'-adenosine monophosphate (cyclic AMP). This increase of cyclic AMP leads to the activation of protein kinase A, which inhibits the phosphorylation of myosin and lowers intracellular ionic calcium concentrations, resulting in relaxation. Albuterol relaxes the smooth muscles of all airways, from the trachea to the terminal bonchioles. Albuterol acts as a functional antagonist to relax the airway irrespective of the spasmogen involved, thus protecting against all bronchoconstrictor challenges. (from Ventolin HFA Product Information)