ALBUTEROL SULFATE- albuterol sulfate solution
Albuterol sulfate inhalation solution is a relatively selective beta 2 -adrenergic bronchodilator (see CLINICAL PHARMACOLOGY section below). Albuterol sulfate, the racemic form of albuterol, has the chemical name α 1 [( tert -Butylamino)methyl]-4-hydroxy- m -xylene-α,α´diol sulfate (2:1) (salt), and the following structural formula:
Albuterol sulfate has a molecular weight of 576.71 and the molecular formula (C 13 H 21 NO 3 ) 2 •H 2 SO 4 . Albuterol sulfate is a white or practically white powder, freely soluble in water and slightly soluble in alcohol.
The World Health Organization recommended name for albuterol base is salbutamol.
Albuterol sulfate inhalation solution 0.083% requires no dilution before administration.
Each mL of albuterol sulfate inhalation solution (0.083%) contains 0.83 mg of albuterol (as 1 mg of albuterol sulfate USP) in an isotonic, sterile, aqueous solution containing sodium chloride, edetate disodium and sodium citrate; hydrochloric acid is used to adjust the pH between 3 and 5. Albuterol sulfate inhalation solution (0.083%) contains no sulfiting agents.
Albuterol sulfate inhalation solution is a clear, colorless solution.
The prime action of beta-adrenergic drugs is to stimulate adenyl cyclase, the enzyme which catalyzes the formation of cyclic-3’,5’-adenosine monophosphate (cyclic AMP) from adenosine triphosphate (ATP). The cyclic AMP thus formed mediates the cellular responses. In vitro studies and in vivo pharmacologic studies have demonstrated that albuterol has a preferential effect on beta 2 -adrenergic receptors compared with isoproterenol. While it is recognized that beta 2 -adrenergic receptors are the predominant receptors in bronchial smooth muscle, 10% to 50% of the beta-receptors in the human heart may be beta 2 -receptors. The precise function of these receptors, however, is not yet established. 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.
Albuterol is longer acting than isoproterenol in most patients by any route of administration because it is not a substrate for the cellular uptake processes for catecholamines nor for catechol-O-methyl transferase.
Studies in asthmatic patients have shown that less than 20% of a single albuterol dose was absorbed following IPPB (intermittent positive-pressure breathing) or nebulizer administration; the remaining amount was recovered from the nebulizer and apparatus and expired air. Most of the absorbed dose was recovered in the urine 24 hours after drug administration. Following a 3 mg dose of nebulized albuterol, the maximum albuterol plasma level at 0.5 hour was 2.1 ng/mL (range 1.4 to 3.2 ng/mL).
There was a significant dose-related response in FEV 1 (forced expiratory volume in one second) and peak flow rate. It has been demonstrated that following oral administration of 4 mg albuterol, the elimination half-life was five to six hours.
Animal studies show that albuterol does not pass the blood-brain barrier. Recent studies in laboratory animals (minipigs, rodents, and dogs) recorded the occurrence of cardiac arrhythmias and sudden death (with histologic evidence of myocardial necrosis) when beta-agonists and methylxanthines were administered concurrently. The significance of these findings when applied to humans is currently unknown.
In controlled clinical trials, most patients exhibited an onset of improvement in pulmonary function within 5 minutes as determined by FEV 1 . FEV 1 measurements also showed that the maximum average improvement in pulmonary function usually occurred at approximately 1 hour following inhalation of 2.5 mg of albuterol by compressor- nebulizer, and remained close to peak for 2 hours. Clinically significant improvement in pulmonary function (defined as maintenance of a 15% or more increase in FEV 1 over baseline values) continued for 3 to 4 hours in most patients and in some patients continued up to 6 hours.
In repetitive dose studies, continued effectiveness was demonstrated throughout the three-month period of treatment in some patients.
Published reports of trials in asthmatic children aged 3 years or older have demonstrated significant improvement in either FEV 1 or PEFR within 2 to 20 minutes following single dose of albuterol inhalation solution. An increase of 15% or more in baseline FEV 1 has been observed in children aged 5 to 11 years up to 6 hours after treatment with doses of 0.10 mg/kg or higher of albuterol inhalation solution. Single doses of 3, 4 or 10 mg resulted in improvement in baseline PER that was comparable to extent and duration to a 2 mg dose, but doses above 3 mg were associated with heart rate increases of more than 10%.
INDICATIONS AND USAGE
Albuterol sulfate inhalation solution is indicated for the relief of bronchospasm in patients 2 years of age and older with reversible obstructive airway disease and acute attacks of bronchospasm.
Albuterol sulfate inhalation solution is contraindicated in patients with a history of hypersensitivity to any of its components.
As with other inhaled beta-adrenergic agonists, albuterol sulfate inhalation solution can produce paradoxical bronchospasm, which can be life threatening. If it occurs, the preparation should be discontinued immediately and alternative therapy instituted.
Fatalities have been reported in association with excessive use of inhaled sympathomimetic drugs and with the home use of nebulizers. It is, therefore, essential that the physician instruct the patient in the need for further evaluation, if his/her asthma becomes worse. In individual patients, any beta 2 -adrenergic agonist, including albuterol solution for inhalation, may have a clinically significant cardiac effect.
Immediate hypersensitivity reactions may occur after administration of albuterol as demonstrated by rare cases of urticaria, angioedema, rash, bronchospasm, and oropharyngeal edema.
Albuterol, as with all sympathomimetic amines, should be used with caution in patients with cardiovascular disorders, especially coronary insufficiency, cardiac arrhythmias and hypertension, in patients with convulsive disorders, hyperthyroidism or diabetes mellitus and in patients who are unusually responsive to sympathomimetic amines.
Large doses of intravenous albuterol have been reported to aggravate preexisting diabetes mellitus and ketoacidosis. As with other beta-agonists, inhaled and intravenous albuterol may produce a significant hypokalemia in some patients, possibly through intracellular shunting, which has the potential to produce adverse cardiovascular effects. The decrease is usually transient, not requiring supplementation.
Repeated dosing with 0.15 mg/kg of albuterol inhalation solution in children aged 5 to 17 years who were initially normokalemic has been associated with an asymptomatic decline of 20% to 25% in serum potassium levels.
Information for Patients
The action of albuterol sulfate inhalation solution may last up to six hours, and therefore it should not be used more frequently than recommended. Do not increase the dose or frequency of medication without medical consultation. If symptoms get worse, medical consultation should be sought promptly. While taking albuterol sulfate inhalation solution, other anti-asthma medicines should not be used unless prescribed.
Drug compatibility (physical and chemical), efficacy, and safety of albuterol inhalation solution when mixed with other drugs in a nebulizer have not been established.
See illustrated “Patient’s Instructions for Use.”
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