clonidine (extended-release, for ADHD)
Brand: Kapvay
Beers Criteria Prototype: clonidine
Drug Class: alpha-2 adrenergic agonist
Drug Family: antihypertensive
Subclass: non-stimulant ADHD medication
Organ Systems: cns
Mechanism of Action
Activates presynaptic and postsynaptic alpha-2 adrenergic receptors in the prefrontal cortex and locus coeruleus. Less selective for alpha-2A than guanfacine; broader alpha-2 and imidazoline receptor activity contributes to more sedation. Reduces norepinephrine release from locus coeruleus, attenuating the noradrenergic hyperarousal in ADHD and PTSD.
alpha-2A adrenergic receptoralpha-2B adrenergic receptoralpha-2C adrenergic receptorimidazoline receptor
Indications
- ADHD (children 6-17 years, monotherapy or adjunct)
- off-label: tic disorders (Tourette syndrome)
- off-label: PTSD-related nightmares and hyperarousal
- off-label: opioid withdrawal adjunct
Contraindications
- hypersensitivity to clonidine
Adverse Effects
Common
- somnolence (more than guanfacine)
- headache
- fatigue
- insomnia (paradoxically at low doses)
- upper abdominal pain
Serious
- severe hypotension
- bradycardia
- heart block
- rebound hypertension on abrupt discontinuation
Pharmacokinetics (ADME)
| Absorption | well absorbed; extended-release achieves lower Cmax and later peak than IR |
| Distribution | protein binding ~20-40%; Vd ~2.1 L/kg |
| Metabolism | hepatic; ~50% excreted unchanged |
| Excretion | primarily renal |
| Half-life | 12-16 hours (ER formulation) |
| Onset | therapeutic effect 2-4 weeks for ADHD |
| Peak | 7-8 hours (ER) |
| Duration | 12 hours per dose (ER) |
| Protein Binding | 20-40% |
| Vd | 2.1 L/kg |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| antihypertensives | additive hypotension | moderate |
| CNS depressants | additive sedation | moderate |
| beta-blockers | rebound hypertension potentiated if both stopped simultaneously; bradycardia | moderate |
Nursing Considerations
- Must taper to discontinue — abrupt cessation causes rebound hypertension that can be severe; reduce dose by 0.1 mg every 3-7 days.
- Somnolence is greater with clonidine ER than guanfacine; dose at bedtime to minimize daytime sedation while still achieving therapeutic effect.
- Monitor blood pressure and heart rate; particularly important in children, who can experience significant hemodynamic effects.
- Not to be confused with immediate-release clonidine (used for hypertension) — the extended-release formulation (Kapvay) is specifically titrated for ADHD dosing.
Clinical Pearls
- Clonidine's broader alpha-2 subtype activity (not just alpha-2A) accounts for its greater sedation compared to guanfacine, but its imidazoline receptor activity (which reduces central sympathetic outflow more broadly) makes it more effective for opioid withdrawal management.
- In ADHD, clonidine is particularly useful when ADHD co-occurs with tic disorders or sleep disturbances, as alpha-2 agonism can reduce both tics and sleep-onset difficulties.
Safety Profile
Pregnancy use-with-caution
Lactation use-with-caution
Renal Adjustment Required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
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