Dichloroisoprenaline

Dichloroisoprenaline, also known as dichlorosisoproterenol or DCI, was the first compound developed that exhibited &beta;-adrenergic receptor antagonist (beta blocker) activity. DCI has low potency and acts as a partial agonist.

Although it was of no clinical value, further developments from DCI eventually led to the development of the clinical candidate pronethalol (withdrawn due to carcinogenicity) and subsequently propranolol (the first clinically-successful beta blocker).