Veterinary Neuropharmacology

β2- adrenergic receptor agonists

β₂ - ADRENERGIC RECEPTOR AGONIST

• In general, β₂ receptor agonists relax smooth muscles of bronchi and uterus and blood vessels of skeletal muscles. At high doses, however, may exhibit β₁ action on heart.
• Tachycardia is common after systemic administration which is due to the agonistic action of β₁ receptors.
• Long term use of β₂ receptor agonists, may result in their down regulation with subsequent decreased pharmacological response.
• Important selective β₂- adrenoceptor stimulant include clenbuterol, terbutaline, isoxuprine, salbutamol (albuterol) and orciprenaline ( metaproterenol). Salbutamol has highest ratio of β₂: β₁action ( about 10 times)
• These are primarily used as bronchodilators and as uterine relaxants to delay premature labour.