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- An alpha-2 receptor agonist licensed for use in hypertension.
- Often used in Critical Care as an additional sedative when sedation is not sufficient on standard drugs. Helps with agitation with tachycardia and hypertension seen during ventilator weaning.
- Dose must not be withdrawn suddenly. Wean off gradually to minimise rebound hypertension and agitation
Mode of action
- Alpha-2 receptor agonist.
- Stimulates alpha receptors in the vasomotor centre of the brainstem. This decreases noradrenaline release and enhances parasympathetic activity; leading to decreased peripheral vascular resistance. Sedative effects may be due to action at the locus coeruleus.
- Hypertension: Clonidine 50-100 micrograms TDS. Increase dose every second or third day. Maximum dose 1.2 mg daily.
- Migraine prevention: Clonidine 50 micrograms BD for 2 weeks, then increased if necessary to 75 micrograms BD
- Needing Sedation and Hypertension Management in ITU
- Loading dose: Clonidine 75 micrograms (5mL of the 150 microgram/mL solution) slow IV over 10 minutes
- Maintenance dose: 0.5-2 microgram/kg/hour. (Max dose 4 microgram/kg/hr).
- Weaning off: Dose reduction of 0.25-0.5 microgram/kg/hr to minimise rebound hypertension and agitation.
- Has been used Unlicensed for Alcohol and Opiate withdrawal reactions and Autonomic storm after traumatic brain injury
- Concurrent use with haloperidol may produce QT prolongation.
- Multiple drug interactions increasing the risk of hypotension, medications should be reviewed in the BNF before use.
- Caution in hypotension, bradycardia or impaired LV function.
- Caution in Raynaud’s syndrome or other occlusive peripheral vascular disease.
- Avoid in Depression and those with Porphyria
- The half-life of clonidine is 10-20 hours, rising to up to 41 hours in end stage renal failure.
- Contraindicated in severe bradyarrhythmia secondary to second- or third-degree AV block or sick sinus syndrome.
- Sedation, constipation, depression, postural hypotension, sleep disorders, vomiting, Raynaud’s phenomenon, AV block.
- In pregnancy should be avoided as can lower fetal heart rate. It is present in breast milk, avoid use in breastfeeding.