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Alpha-2 Agonist — Analgesic Adjunct / Sedation Pregnancy: Use with caution — crosses placenta; neonatal bradycardia reported

Clonidine

Brand names: Catapres, Duraclon (epidural)

Adult dose

Dose: Epidural adjunct: 75-150 micrograms. IV adjunct: 1-3 micrograms/kg slowly. Oral: 50-200 micrograms three times daily
Route: Oral / IV / Epidural / Peripheral nerve block adjunct
Frequency: As needed (IV/epidural); three times daily (oral)
Max: Epidural: 150 micrograms; IV perioperative: 3 micrograms/kg
As local anaesthetic adjunct (epidural/nerve block): prolongs block duration and improves analgesia quality. Perineural clonidine 75-150 micrograms extends peripheral nerve block by 2-4 hours

Paediatric dose

Dose: 1-2 micrograms/kg IV (sedation adjunct); 1-2 micrograms/kg caudal adjunct micrograms/kg
Route: IV / Caudal / Oral
Frequency: Single dose (IV/caudal); two to three times daily (oral)
Max: 150 micrograms (caudal)
Caudal adjunct: 1-2 micrograms/kg added to local anaesthetic extends caudal block duration by 2-4 hours

Dose adjustments

Renal

Reduce dose in renal impairment — primarily renally excreted

Hepatic

No significant adjustment required

Paediatric weight-based calculator

Caudal adjunct: 1-2 micrograms/kg added to local anaesthetic extends caudal block duration by 2-4 hours

Clinical pearls

  • Perineural clonidine as local anaesthetic adjunct: alpha-2 receptors on peripheral nerves mediate analgesia; 75-150 micrograms added to peripheral nerve block solution extends duration by 2-4 hours — well-established in regional anaesthesia
  • Clonidine in paediatric caudal anaesthesia: 1-2 micrograms/kg significantly extends caudal block duration — used routinely in paediatric regional anaesthesia to reduce post-operative analgesic requirements
  • Opioid-sparing: reduces anaesthetic and opioid requirements intraoperatively by 25-40% — central alpha-2 agonism attenuates nociception
  • Rebound hypertension: abrupt withdrawal after chronic oral use causes hypertensive crisis — always taper; use patch formulation for reliable delivery in perioperative period
  • Dexmedetomidine (highly selective alpha-2 agonist) is now preferred over clonidine for IV sedation — higher alpha-2:alpha-1 selectivity ratio means more predictable sedation with less vasoconstriction

Contraindications

  • Severe bradycardia or heart block (without pacemaker)
  • Sick sinus syndrome
  • Rebound hypertension risk (abrupt withdrawal after chronic use)

Side effects

  • Bradycardia and hypotension
  • Sedation
  • Dry mouth
  • Rebound hypertension on abrupt withdrawal (chronic use)
  • Dizziness

Interactions

  • Beta-blockers (severe bradycardia — additive)
  • Antihypertensives (enhanced hypotension)
  • TCAs (reduce clonidine antihypertensive effect)
  • CNS depressants (additive sedation)

Monitoring

  • Heart rate (bradycardia)
  • Blood pressure
  • Sedation level
  • Block duration (if used as adjunct)

Reference: BNFc; BNF 90; Catapres SPC; PROSPECT Clonidine Review; Eisenach et al. (perineural clonidine); AAGBI. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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