Isoproterenol hydrochloride or Isoprenaline (Medihaler-Iso®) is a beta adrenergic receptor agonist medication, used as an inhaled aerosol to treat asthma. Although it activates all beta adrenergic receptors, it works in a similar fashion to the more selective beta2-adrenergic receptor agonists e.g. salbutamol, by relaxing the airways to increase airflow.