Chemistry - A synthetic sympathomimetic amine, albuterol sulfate occurs as a white, almost tasteless crystalline powder. It is soluble in water and slightly soluble in alcohol. One mg of albuterol is equivalent to 1.2 mg of albuterol sulfate. Albuterol is also known as salbutamol .
Storage/Stability/Compatibility - Oral albuterol sulfate products should be stored at 2-30°C. The capsules containing powder for inhalation should be left in the original packaging until just before use.
Pharmacology - Like other beta-agonists, albuterol is believed to act by stimulating production of cyclic AMP through activation of adenyl cyclase. Albuterol is considered to be predominantly a beta2 agonist (relaxation of bronchial, uterine, and vascular smooth muscles). At usual doses, albuterol possesses minimal beta1 agonist (heart) activity. beta adrenergics can promote a shift of potassium away from the serum and into the cell, perhaps via stimulation of Na+-K+-ATPase. Temporary decreases in either normal or high serum potassium levels are possible.
Uses/Indications - Albuterol is used principally in dogs and cats for its effects on bronchial smooth muscle to alleviate bronchospasm or cough. It potentially could also be used in horses as a bronchodilator.
Pharmacokinetics - The specific pharmacokinetics of this agent have apparently not been thoroughly studied in domestic animals. In general, albuterol is absorbed rapidly and well after oral administration. Effects occur within 5 minutes after oral inhalation, and 30 minutes after oral administration (e.g., tablets). It does not cross the blood-brain barrier, but does cross the placenta. Duration of effect generally persists for 3-6 hours after inhalation and up to 12 hours (depending on dosage form) after oral administration. The drug is extensively metabolized in the liver, principally to the inactive metabolite, albuterol 4’-O-sulfate. After oral administration, the serum half life in humans has been reported as 2.7-5 hours.
Contraindications/Precautions/Reproductive Safety - Albuterol is contraindicated in patients hypersensitive to it. One veterinary school formulary (Schultz 1986) states that a related drug (terbutaline), is contraindicated in dogs and cats with heart disease, particularly when CHF or cardiomyopathy is present. It should be used with caution in patients with diabetes, hyperthyroidism, hypertension, seizure disorders, or cardiac disease (especially with concurrent arrhythmias).
In very large doses, albuterol is teratogenic in rodents. It should be used (particularly the oral dosage forms) during pregnancy only when the potential benefits outweigh the risks. Like some other beta agonists, it may delay pre-term labor after oral administration. It is unknown whether the drug crosses into maternal milk.
Adverse Effects/Warnings - Most adverse effects are dose-related and are those that would be expected with sympathomimetic agents including increased heart rate, tremors, CNS excitement (nervousness) and dizziness. These effects are generally transient and mild and usually do not require discontinuation of therapy. Decreased serum potassium values may be noted; rarely is potassium supplementation required.
Overdosage/Acute Toxicity - Symptoms of significant overdose after systemic administration may include arrhythmias (bradycardia, tachycardia, heart block, extrasystoles), hypertension, fever, vomiting, mydriasis, and CNS stimulation. Hypokalemia may also be noted. If recently ingested (orally), and if the animal does not have significant cardiac or CNS effects, it should be handled like other overdoses (empty gut, give activated charcoal and a cathartic). If cardiac arrhythmias require treatment, a beta-blocking agent (e.g., propranolol) can be used, but may precipitate bronchoconstriction. The oral LD50 in rats is reported to be greater than 2 g/kg. Contact a poison control center for further information.
Drug Interactions - Use of albuterol with other sympathomimetic amines may increase the risk of developing adverse cardiovascular effects. Beta-adrenergic blocking agents (e.g., propranolol) may antagonize the actions of albuterol. Tricyclic antidepressants or monoamine oxidase inhibitors may potentiate the vascular effects of albuterol. Use with inhalation anesthetics (e.g., halothane, isoflurane, methoxyflurane), may predispose the patient to ventricular arrhythmias, particularly in patients with preexisting cardiac disease—use cautiously. Use with digitalis glycosides may increase the risk of cardiac arrhythmias.
a) 8 micrograms / kg q 12 hours PO (Enos, 1993)
Monitoring Parameters - 1) Clinical symptom improvement; auscultation, blood gases (if indicated); 2) Cardiac rate, rhythm (if warranted); 3) Serum potassium, early in therapy if animal susceptible to hypokalemia
Client Information - Contact veterinarian if animal’s condition deteriorates or becomes acutely ill.
Dosage Forms/Preparations/FDA Approval Status/Withholding Times –
Veterinary-Approved Products: None
Albuterol ;Tablets 2 mg, 4 mg tablets & 4 mg, 8 mg extended release tablets; Proventil ® (Schering); Proventil Repetabs ®; Ventolin ® (Glaxo Wellcome); Volmax (Muro); generic (Rx)
Albuterol Oral Syrup 2 mg (as sulfate)/5 ml; Proventil® (Schering); Ventolin® (Glaxo Wellcome); Generic; (Rx)
Albuterol Aerosol: Each actualization delivers 90 mcg albuterol in 17g & 6.7g canisters; Proventil® (Schering); Proventil HFA® (Key); Ventolin® (Glaxo Wellcome); generic. (Rx)
Albuterol for Inhalation: Solution for Inhalation 0.083% & 0.5% (as sulfate) in 3 ml or 20 ml; 200 micrograms capsules (powder) for inhalation; Airet® (Adams); Albuterol (Dey, Copley); Proventil ® (Schering);Ventolin Nebules® (Glaxo Wellcome); Ventolin Rotacaps® (Glaxo Wellcome); generic. (Rx)
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