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Clonidine
💊 About: Always check the BNF link here
- An alpha-2 receptor agonist licensed for hypertension.
- Widely used in Critical Care as an additional sedative when standard sedatives are insufficient — particularly useful in agitation with tachycardia and hypertension during ventilator weaning.
- ⚠️ Must not be withdrawn suddenly ➝ wean gradually to avoid rebound hypertension and agitation.
⚙️ Mode of Action
- Stimulates central alpha-2 receptors in the vasomotor centre of the brainstem.
- ↓ Noradrenaline release + ↑ parasympathetic tone ➝ reduces peripheral vascular resistance.
- Sedative effects may relate to action at the locus coeruleus.
💉 Dose
- Hypertension: 50–100 micrograms TDS; increase every 2–3 days. Max: 1.2 mg/day.
- Migraine prevention: 50 micrograms BD × 2 weeks → increase if required to 75 micrograms BD.
- ICU sedation / hypertension management:
- Loading dose: 75 micrograms (5 mL of 150 mcg/mL solution) slow IV over 10 min.
- Maintenance: 0.5–2 micrograms/kg/hr (max 4 mcg/kg/hr).
- Weaning: Reduce by 0.25–0.5 mcg/kg/hr to minimise rebound hypertension & agitation.
- 📌 Used off-label for alcohol/opiate withdrawal and autonomic storm post-traumatic brain injury.
🔄 Interactions
- + Haloperidol → possible QT prolongation.
- Multiple other interactions may increase risk of hypotension (always cross-check with BNF).
⚠️ Cautions
- Hypotension, bradycardia, impaired LV function.
- Raynaud’s or other occlusive peripheral vascular disease.
- Avoid in depression and porphyria.
- 📌 Half-life: 10–20 hrs, prolonged up to 41 hrs in ESRF.
🚫 Contraindications
- Severe bradyarrhythmia due to 2nd/3rd-degree AV block or sick sinus syndrome.
❗ Side Effects
- Sedation, constipation, postural hypotension, sleep disturbance, depression, vomiting, AV block, Raynaud’s.
- Pregnancy: avoid (↓ fetal heart rate). Breastfeeding: avoid (present in milk).
📚 References
| The content on this website is provided for educational and informational purposes only to support exam preparation (e.g., MLA, MRCP, USMLE) and learning. This is NOT medical advice, diagnosis, treatment, or professional guidance. It does not replace consultation with a qualified healthcare professional, official guidelines (e.g., NICE, GMC, BNF), or supervised clinical practice. Always verify information with current, authoritative sources. Makindo and its contributors accept no liability for any reliance on this content, including errors, omissions, or any resulting harm, loss, or consequences. By using this site, you agree to these terms. |
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