MODESTO XR 3MG is a sustained-release tablet containing 3 milligrams of guanfacine. Guanfacine is an alpha-2A adrenergic receptor agonist primarily used to treat attention-deficit hyperactivity disorder (ADHD) in children, adolescents, and adults. 1 The extended-release formulation allows for once-daily dosing, providing a more consistent level of the medication throughout the day to help improve attention, reduce impulsivity, and decrease hyperactivity. It works by affecting certain brain chemicals, leading to improved focus and behavioral control.