Isoproterenol treats congestive heart failure, heart attack and asthma. It is a bronchodilator, a drug that widens the bronchi and increases airflow to the lungs. Isoproterenol is available as a sterile injection, infusion and metered dose inhaler. Isoproterenol may be helpful for those with asthma or chronic obstructive pulmonary disease. Isoproterenol requires a doctor's prescription.