Clonidine (Catapres)
Centrally-acting alpha-2 adrenergic agonist that reduces sympathetic outflow from the brainstem, lowering blood pressure, heart rate, and plasma catecholamines. Also used for ADHD, opioid withdrawal, Tourette syndrome, and menopausal flushing. Abrupt discontinuation causes rebound hypertension due to compensatory upregulation of adrenergic tone — must be tapered over 2-4 days. Half-life 12-16h; 50% excreted renally unchanged. Available as oral tablet and transdermal patch (Catapres-TTS).
Projected serum levels — 0.10 mg, twice daily
Maintenance schedule: 0.10 mg twice daily (oral).
Loading schedule: 0.23 mg on day 1, then 0.10 mg twice daily — reaching therapeutic levels sooner.
Modeled steady state after ~2 days: peak ≈ 0.19 mg, trough ≈ 0.11 mg body load. Population-based estimate over 15 days for a 0.10 mg dose at a 70 kg reference body mass — the interactive app scales curves to your doses, timing, and body mass.
Key facts
- Category
- Antihypertensive / Alpha-2 Agonist
- Route modeled
- Oral
- Model confidence
- inferred
- Half-life
- 14 h
- Common dose
- 0.10 mg
- Suggested maximum
- 0.60 mg/day
- Reference dose range
- 0.050–0.60 mg (single dose)
- Suggested cadence
- twice daily
- Validated against
- 0.10 mg oral — Cmax 0.000 mg/L at 3 h
Research behind this entry
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Clonidine in patients undergoing noncardiac surgery
Landmark POISE-2 trial (n=10,010) — perioperative clonidine did not reduce death or nonfatal MI after noncardiac surgery but significantly increased hypotension (RR 1.32) and nonfatal cardiac arrest (RR 3.18).…
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Clonidine withdrawal: mechanism and frequency of rebound hypertension
Definitive early study documenting the clonidine withdrawal phenomenon — rebound hypertension with plasma catecholamine surge, tachycardia, and subjective distress upon abrupt discontinuation. Demonstrated that the…
2 published studies referenced in the app, each with a plain-language summary.