Alpha-2 adrenergic agonist
Stimulates central alpha-2 receptors, reducing sympathetic outflow, which lowers blood pressure and modulates noradrenergic activity involved in attention, arousal, and autonomic regulation.
Hypertension, attention-deficit/hyperactivity disorder (ADHD) in children aged 6 years and older
Opioid withdrawal, Tourette syndrome, anxiety disorders, sleep disturbances, post-traumatic stress disorder (PTSD)-related hyperarousal and sleep disturbances, agitation and aggression in neurodevelopmental disabilities (especially with hyperactivity or impulsivity)
Immediate-release oral tablets (Catapres), extended-release oral tablets (Kapvay), transdermal patch
IR: Start 0.025–0.05 mg p.o. in the morning, titrate slowly based on clinical response, typical total 0.2–0.3 mg/day divided into 3–4 doses; ER: Start 0.1 mg p.o. nightly, increase by 0.1 mg weekly based on clinical response, typical total 0.1–0.4 mg/day divided twice daily.
0.1–0.4 mg/day
Metabolized hepatically, excreted renally. Half-life approximately 12–16 hours; ER formulation modifies the absorption profile without affecting elimination half-life.
Drowsiness, dry mouth, constipation, hypotension, fatigue
Rebound hypertension with abrupt discontinuation—taper gradually
Monitor blood pressure and heart rate regularly, especially during dose changes or discontinuation
None
Use caution in elderly patients due to increased risk of hypotension and orthostatic falls. IR forms may be preferred for tics or when flexible dosing is needed, while ER provides smoother coverage and is often used for ADHD. Clonidine may improve impulsivity and irritability in intellectual disabilities and neurodevelopmental disorders. It can be used for insomnia due to its sedative properties, ability to increase total sleep time, and favorable tolerability in select populations. In traumatic brain injury (TBI), it is used off-label for posttraumatic headache prophylaxis and trauma-related nightmares, particularly when comorbid with PTSD.