What are the common indications and dosing regimes of clonidine?
Indications & Dosing
Indications & Dosing
Sedation on critical care
- Sedation of intubated and mechanically ventilated patients as an adjunct to other sedatives
- Treatment of agitated and delirious patients
- Must be weaned gradually
IV infusion: 0.5-1.0 mcg/kg/hr
IV/PO: 50-200 mcg QDS
IV/PO: 50-200 mcg QDS
Adjunct to anaesthesia
- Reduces MAC of volatile agents
IV: 1–2 mcg/kg
Adjunct to perioperative analgesia
IV: 1–2 mcg/kg
Adjunct to regional anaesthesia
- Prolongs duration of effect
- Useful in peripheral nerve, epidural, caudal and spinal blocks
Anxiolysis (Premedication)
- May be a useful in both children and adults (though onset is slow)
PO: 4 mcg/kg
Antihypertensive
- Medical use is limited by severe rebound hypertension following discontinuation
- May be useful for hypotensive anaesthesia
Alcohol & opiate withdrawal
PO: 0.6-1.2 mg/day in divided doses
Postoperative shivering
IV/PO: up to 0.5 mcg/kg (low dose)
Migraine prophylaxis
PO: low dose
Contraindications
Contraindications
- No definitive contraindications
- Extreme caution should be exercised in patients with:
- Heart block
- Bradycardia
- Hypotension or hypovolaemia
- Severe ventricular dysfunction
- Peripheral vascular disease
- Concomitant use of:
- Beta-blockers (bradycardia)
- Tricyclic antidepressants (counteract effect)
- Digoxin (bradycardia)
- Haloperidol (prolongation of QT interval)
- Sudden withdrawal should be avoided due to the risk of rebound hypertension
- No definitive contraindications
- Extreme caution should be exercised in patients with:
- Heart block
- Bradycardia
- Hypotension or hypovolaemia
- Severe ventricular dysfunction
- Peripheral vascular disease
- Concomitant use of:
- Beta-blockers (bradycardia)
- Tricyclic antidepressants (counteract effect)
- Digoxin (bradycardia)
- Haloperidol (prolongation of QT interval)
- Sudden withdrawal should be avoided due to the risk of rebound hypertension
What is the mechanism of action of clonidine?
Mechanism of Action
Mechanism of Action
- Selective agonist at presynaptic alpha-2 adrenoceptors:
- Less selective than dexmedetomidine with ratio of alpha-1:alpha-2 1:200
- Acts particularly on the locus coeruleus in the floor of the fourth ventricle, producing depression of thalamic transmission to the cerebral cortex
- Primarily responsible for sedation, anxiolysis and analgesia
- Reduce sympathetic outflow resulting in hypotension and bradycardia
- Some activity at alpha-1 receptors:
- Produces vasoconstriction at higher doses
- Produces centrally mediated hypotension
- Selective agonist at presynaptic alpha-2 adrenoceptors:
- Less selective than dexmedetomidine with ratio of alpha-1:alpha-2 1:200
- Acts particularly on the locus coeruleus in the floor of the fourth ventricle, producing depression of thalamic transmission to the cerebral cortex
- Primarily responsible for sedation, anxiolysis and analgesia
- Reduce sympathetic outflow resulting in hypotension and bradycardia
- Some activity at alpha-1 receptors:
- Produces vasoconstriction at higher doses
- Produces centrally mediated hypotension