Central alpha-2 agonists

Central alpha-2 agonists stimulate alpha-2 receptors in the brainstem, which reduces the nerve signals that tighten blood vessels and speed up the heart. Clonidine treats high blood pressure, and some extended-release forms are used for ADHD. Drowsiness, dry mouth, dizziness, and constipation are common. Stopping them suddenly can cause a dangerous rebound rise in blood pressure, so they are tapered off gradually.

• ClonidineKnown brand names include Catapres.