Isoprenaline is a medication used for the treatment of bradycardia (slow heart rate), heart block, and rarely for asthma. It is a non-selective beta-adrenergic agonist and structurally similar to adrenaline. Isoprenaline is a β1- and β2-adrenoreceptor agonist which was commonly used to treat asthma before the more widespread use of albuterol, which has more selective effects on the airways. Its route of administration is either intravenous, oral, intranasal, subcutaneous, or intramuscular, depending on use. The plasma half-life for isoprenaline is approximately two hours. Isoprenaline's effects on the cardiovascular system (non-selective) relate to its actions on cardiac β1 receptors and β2 receptors on smooth muscle within the tunica media of arterioles. Isoprenaline has positive inotropic and chronotropic effects on the heart. β2--adrenoceptor stimulation in arteriolar smooth muscle induces vasodilation.