Albuterol

12.1 Mechanism of Action In vitro studies and in vivo pharmacologic studies have demonstrated that albuterol has a preferential effect on beta 2 -adrenergic receptors compared with isoproterenol. Although beta 2 -adrenoceptors are the predominant adrenergic receptors in bronchial smooth muscle and beta 1 -adrenoceptors are the predominant receptors in the heart, there are also beta 2 -adrenoceptors in the human heart comprising 10% to 50% of the total beta-adrenoceptors. The precise function of these receptors has not been established, but their presence raises the possibility that even selective beta 2 -agonists may have cardiac effects. Activation of beta 2 -adrenergic receptors on airway smooth muscle leads to the activation of adenyl cyclase 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 bronchioles. Albuterol acts as a functional antagonist to relax the airway irrespective of the spasmogen involved, thus protecting against all bronchoconstrictor challenges. Increased cyclic AMP concentrations are also associated with the inhibition of release of mediators from mast cells in the airway. Albuterol has been shown in most controlled clinical trials to have more effect on the respiratory tract, in the form of bronchial smooth muscle relaxation, than isoproterenol at comparable doses while producing fewer cardiovascular effects. Controlled clinical studies and other clinical experience have shown that inhaled albuterol, like other beta-adrenergic agonist drugs, can produce a significant cardiovascular effect in some patients, as measured by pulse rate, blood pressure, symptoms, and/or electrocardiographic changes [see Warnings a

1 INDICATIONS AND USAGE Albuterol Sulfate HFA is a beta 2 -adrenergic agonist indicated for: Treatment or prevention of bronchospasm in adult and pediatric patients aged 4 years and older with reversible obstructive airway disease. ( 1.1 ) Prevention of exercise-induced bronchospasm in adult and pediatric patients aged 4 years and older. ( 1.2 ) 1.1 Bronchospasm Albuterol Sulfate HFA Inhalation Aerosol is indicated for the treatment or prevention of bronchospasm in adult and pediatric patients aged 4 years and older with reversible obstructive airway disease. 1.2 Exercise-Induced Bronchospasm Albuterol Sulfate HFA is indicated for the prevention of exercise-induced bronchospasm in adult and pediatric patients aged 4 years and older.

2 DOSAGE AND ADMINISTRATION For oral inhalation only. ( 2 ) Treatment or prevention of bronchospasm in adult and pediatric patients aged 4 years and older: 2 inhalations by oral inhalation every 4 to 6 hours. For some patients, 1 inhalation every 4 hours may be sufficient. ( 2.1 ) Prevention of exercise-induced bronchospasm in adult and pediatric patients aged 4 years and older: 2 inhalations by oral inhalation 15 to 30 minutes before exercise. ( 2.2 ) Priming information: Prime Albuterol Sulfate HFA before using for the first time, when the inhaler has not been used for more than 2 weeks, or when the inhaler has been dropped. To prime Albuterol Sulfate HFA, release 4 sprays into the air away from the face, shaking well before each spray. ( 2.3 ) Cleaning information: At least once a week, wash the actuator with warm water and let it air-dry completely. ( 2.3 ) 2.1 Recommended Dosage for Bronchospasm (Acute Episodes or Symptoms Associated with Bronchospasm) Adult and pediatric patients aged 4 years and older: 2 inhalations by oral inhalation repeated every 4 to 6 hours; in some patients, 1 inhalation every 4 hours may be sufficient. More frequent administration or a greater number of inhalations is not recommended. 2.2 Recommended Dosage for Prevention of Exercise-Induced Bronchospasm Adult and pediatric patients aged 4 years and older: 2 inhalations by oral inhalation 15 to 30 minutes before exercise. 2.3 Administration Information Albuterol Sulfate HFA should be administered by the orally inhaled route only. Priming Priming Albuterol Sulfate HFA is essential to ensure appropriate albuterol content in each actuation. Prime Albuterol Sulfate HFA before using for the first time, when the inhaler has not been used for more than 2 weeks, or when the inhaler has been dropped. To prime Albuterol Sulfate HFA, release 4 sprays into the air away from the face, shaking well before each spray. Avoid spraying in eyes. Cleaning To ensure proper dosing and to prevent actuator orifice blockage, wash the actuator with warm water and let it air-dry completely at least once a week.

6 ADVERSE REACTIONS The following clinically significant adverse reactions are described elsewhere in the labeling: Paradoxical bronchospasm [see Warnings and Precautions ( 5.1 )] Cardiovascular effects [see Warnings and Precautions ( 5.4 )] Hypersensitivity reactions, including anaphylaxis [see Warnings and Precautions ( 5.6 )] Hypokalemia [see Warnings and Precautions ( 5.8 )] Most common adverse reactions (incidence ≥3%) are throat irritation, viral respiratory infections, upper respiratory inflammation, cough, and musculoskeletal pain. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Prasco Laboratories at 1-866-525-0688 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice. The safety data described below reflects exposure to albuterol sulfate HFA in 248 subjects treated with albuterol sulfate HFA in 3 placebo-controlled clinical trials of 2 to 12 weeks’ duration. The data from adults and adolescents is based upon 2 clinical trials in which 202 subjects with asthma aged 12 years and older were treated with albuterol sulfate HFA 2 inhalations 4 times daily for 12 weeks’ duration. The adult/adolescent population was 92 female, 110 male and 163 white, 19 black, 18 Hispanic, 2 other. The data from pediatric subjects are based upon 1 clinical trial in which 46 subjects with asthma aged 4 to 11 years were treated with albuterol sulfate HFA 2 inhalations 4 times daily for 2 weeks’ duration. The population was 21 female, 25 male and 25 white, 17 black, 3 Hispanic, 1 other. Adult and Adolescent Subjects Aged 12 Years and Older The two 12-week, randomized, double-blind trials in 610 adult and adolescent subjects with asthma that compared albuterol sulfate HFA, a CFC 11/12-propelled albuterol inhaler, and an HFA-134a placebo inhaler. Overall, the incidence and nature of the adverse reactions reported for albuterol sulfate HFA and a CFC 11/12‑propelled albuterol inhaler were comparable. Table 1 lists the incidence of all adverse reactions (whether considered by the investigator to be related or unrelated to drug) from these trials that occurred at a rate of ≥3% in the group treated with albuterol sulfate HFA and more frequently in the group treated with albuterol sulfate HFA than in the HFA-134a placebo inhaler group. Table 1. Adverse Reactions with Albuterol Sulfate HFA with ≥3% Incidence and More Common than Placebo in Adult and Adolescent Subjects Adverse Reaction Percent of Subjects Albuterol Sulfate HFA (n = 202) % CFC 11/12-Propelled Albuterol Inhaler (n = 207) % Placebo HFA-134a (n = 201) % Ear, nose, and throat Throat irritation 10 6 7 Upper respiratory inflammation 5 5 2 Lower respiratory Viral respiratory infections 7 4 4 Cough 5 2 2 Musculoskeletal Musculoskeletal pain 5 5 4 Adverse reactions reported by <3% of the adult and adolescent subjects receiving albuterol sulfate HFA and by a greater proportion of subjects receiving albuterol sulfate HFA than receiving HFA-134a placebo inhaler and that have the potential to be related to albuterol sulfate HFA include diarrhea, laryngitis, oropharyngeal edema, cough, lung disorders, tachycardia, and extrasystoles. Palpitations and dizziness have also been observed with albuterol sulfate HFA. Pediatric Subjects Aged 4 to 11 Years Results from the 2-week clinical trial in pediatric subjects with asthma aged 4 to 11 years showed that this pediatric population had an adverse reaction profile similar to that of the adult and adolescent populations. Three trials have been conducted to evaluate the safety and efficacy of albuterol sulfate HFA in subjects between birth and 4 years of age. The results of these trials did not establish the efficacy of albuterol sulfate HFA in this age group [see Use in Specific Populations ( 8.4 )] . Since the efficacy of albuterol sulfate HFA has not been demonstrated in children between birth and 48 months of age, the safety of albuterol sulfate HFA in this age-group cannot be established. However, the safety profile observed in the pediatric population younger than 4 years was comparable to that observed in the older pediatric subjects and in adults and adolescents. Where adverse reaction incidence rates were greater in subjects younger than 4 years compared with older subjects, the higher incidence rates were noted in all treatment arms, including placebo. These adverse reactions included upper respiratory tract infection, nasopharyngitis, pyrexia, and tachycardia. 6.2 Postmarketing Experience In addition to adverse reactions reported from clinical trials, the following adverse reactions have been identified during postapproval use of albuterol sulfate. Because these reactions are reported voluntarily from a population of uncertain size, it i

7 DRUG INTERACTIONS Other short-acting sympathomimetic aerosol bronchodilators should not be used concomitantly with albuterol. If additional adrenergic drugs are to be administered by any route, they should be used with caution to avoid deleterious cardiovascular effects. Beta-blockers: Use with caution. May block bronchodilatory effects of beta-agonists and produce severe bronchospasm. ( 7.1 ) Diuretics: Use with caution. Electrocardiographic changes and/or hypokalemia associated with non–potassium-sparing diuretics may worsen with concomitant beta-agonists. ( 7.2 ) Digoxin: May decrease serum digoxin levels. Consider monitoring digoxin levels. ( 7.3 ) Monoamine oxidase inhibitors and tricyclic antidepressants: Use with extreme caution. May potentiate effect of albuterol on vascular system. ( 7.4 ) 7.1 Beta-Adrenergic Receptor Blocking Agents Beta-blockers not only block the pulmonary effect of beta-agonists, such as albuterol sulfate HFA, but may also produce severe bronchospasm in patients with asthma. Therefore, patients with asthma should not normally be treated with beta-blockers. However, under certain circumstances, there may be no acceptable alternatives to the use of beta-adrenergic blocking agents for these patients; cardioselective beta-blockers could be considered, although they should be administered with caution. 7.2 Non–Potassium-Sparing Diuretics The ECG changes and/or hypokalemia that may result from the administration of non—potassium-sparing diuretics (such as loop or thiazide diuretics) can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is not known, caution is advised in the coadministration of Albuterol Sulfate HFA with non–potassium-sparing diuretics. 7.3 Digoxin Mean decreases of 16% to 22% in serum digoxin levels were demonstrated after single-dose intravenous and oral administration of albuterol, respectively, to normal volunteers who had received digoxin for 10 days. The clinical relevance of these findings for patients with obstructive airway disease who are receiving inhaled albuterol and digoxin on a chronic basis is unclear. Nevertheless, it would be prudent to carefully evaluate the serum digoxin levels in patients who are currently receiving digoxin and albuterol. 7.4 Monoamine Oxidase Inhibitors and Tricyclic Antidepressants Albuterol Sulfate HFA should be administered with extreme caution to patients being treated with monoamine oxidase inhibitors or tricyclic antidepressants, or within 2 weeks of discontinuation of such agents, because the action of albuterol on the vascular system may be potentiated.