Guanfacine has which one of the following effects on blood pressure?

Guanfacine is primarily an alpha-2 adrenergic agonist that works by stimulating these receptors in the central nervous system. This stimulation leads to a reduction in sympathetic outflow, which in turn reduces the release of norepinephrine and decreases peripheral vascular resistance. As a result, the overall effect of guanfacine is a decrease in blood pressure.

This mechanism of action is particularly relevant in the treatment of hypertension, making the drug effective in lowering blood pressure in patients. Additionally, the drug is often used in the management of attention deficit hyperactivity disorder (ADHD), but its antihypertensive properties are significant as well. Therefore, stating that guanfacine decreases blood pressure is accurate based on its pharmacological action.