Which statement best describes the effects of the positive enantiomer of dobutamine?

Which statement best describes the effects of the positive enantiomer of dobutamine?

• A. It acts as a Beta-1 and Beta-2 agonist with Alpha-1 antagonist effect
• B. It acts as a Beta-1 and Beta-2 agonist with Alpha-1 agonist effect
• C. It has no impact on beta receptors
• D. It is a strong Alpha-1 agonist

Answer: (A)

The positive (dextrorotatory) enantiomer of dobutamine mainly drives beta-adrenergic effects. It stimulates beta-1 receptors to boost myocardial contractility and also activates beta-2 receptors, which promotes mild vasodilation. Importantly, it counteracts alpha-1–mediated vasoconstriction, acting as an alpha-1 antagonist. The result is an increased cardiac output from stronger heart contractions with little or even a slight decrease in systemic vascular resistance. This combination explains why the best description is beta-1 and beta-2 agonism with alpha-1 antagonism.

The positive (dextrorotatory) enantiomer of dobutamine mainly drives beta-adrenergic effects. It stimulates beta-1 receptors to boost myocardial contractility and also activates beta-2 receptors, which promotes mild vasodilation. Importantly, it counteracts alpha-1–mediated vasoconstriction, acting as an alpha-1 antagonist. The result is an increased cardiac output from stronger heart contractions with little or even a slight decrease in systemic vascular resistance. This combination explains why the best description is beta-1 and beta-2 agonism with alpha-1 antagonism.