Clonidine

See Alpha Adrenergic Central Agonist
See Alpha Adrenergic Receptor
Central Acting Adrenergic Agonists
1. Activates alpha-2 receptors that inhibit CNS preganglionic sympathetic signals, lowering Blood Pressure
2. Results in increased parasympathetic effects and side effects (e.g. sedation)

Renal excretion (unchanged in urine)
1. Decrease dose in Renal Insufficiency, including starting dose
2. Observe for adverse effects (Bradycardia, Hypotension)
Oral Dosing
1. Readily absorbed with 70% Bioavailability
2. Activity
  1. Onset in 30-60 min
  2. Duration: 6-10 hours

See Clonidine Withdrawal
Acute withdrawal risk with rebound Hypertension
1. Do not stop suddenly (esp. if Clonidine dose >1.2 mg per day)

Hypertension (adults)
1. Start 0.1 mg orally twice daily
2. Titrate dose weekly, modifying total daily dose 0.1 mg/day to typical dose of 0.2 to 0.6 mg/day divided twice daily
3. Maximum total daily dose: 2.4 mg/day
Hypertensive Urgency (adults, other agents are preferred for Hypertensive Urgency )
1. Start: 0.2 mg oral load
2. Titrate 0.1 mg/hour to:
  1. Maximum of 0.7 mg
  2. Diastolic Blood Pressure drops more than 20 mmHg
Hypertension (children)
1. Start 5 to 7 mcg/kg/day orally divided every 6 to 12 hours
2. Titrate dose weekly, modifying total daily dose 5-25 mcg/kg/day in divided doses (maximal dose 0.9 mg/day)
Hot Flushes
1. Start 0.1 mg orally at bedtime (or transdermal patch)
2. May titrate up to 0.2 mg orally twice daily

Not recommended for use in children
Available in 0.1, 0.2 and 0.3 mg/day patches (may combine patches up to two of the 0.3 mg/day patches)
Start with a 0.1 mg/day patch
1. Titrate to effective dose, up to maximum effective dose of 0.6 mg/day (two of the 0.3 mg/day patches)
Costs $40-100/month (depending on dose)
Changed every 7 days
Does not reach peak effect for 2-3 days
Once at level, delivers constant Clonidine rate over 7 days
Transition from oral to patch
1. Day 1
  1. Apply transdermal Clonidine
  2. Take full oral Clonidine dose
2. Day 2
  1. Take 50% of oral Clonidine dose
3. Day 3
  1. Take 25% of oral Clonidine dose
  2. Discontinue oral Clonidine

See Clonidine Overdose
See Alpha Adrenergic Central Agonist
Somnolence
Headache
Dry Mouth
Constipation
Bradycardia
1. Risk of Sinus Node Dysfunction and Atrioventricular Block
2. Increased risk when combined with Digoxin, Beta Blockers, nondihydropyridine Calcium Channel Blockers
Hypotension
Rebound Hypertension (if abruptly discontinued at higher dose)
1. See Clonidine Withdrawal
2. Risk increases with total daily doses >0.7 mg/day (esp. >1.2 mg/day)
3. Slowly taper dose every 3 to 7 days to prevent rebound Hypertension
4. Continue in Clonidine in the perioperative period
Sodium and water retention
1. Reflex renin release in response to excessive Clonidine and renal hypoperfusion