Isoprenaline (INN) or isoproterenol (USAN, trade names Medihaler-Iso and Isuprel) is a medication used for the treatment of bradycardia (slow heart rate), heart block, and rarely for asthma.In humans, it is a non-selective beta-adrenergic agonist and TAAR1 agonist that is structurally similar to adrenaline.ses [edit]. Its primary use is for bradycardia or heart block. By activating β 1 -receptors on the heart, it induces positive chronotropic, dromotropic, and inotropic effects. It can be used as an inhaled aerosol to treat asthma, although this is currently a rare treatment.