Clonidine is a medicine that lowers blood pressure by acting on the brain. It is also used for neuropathic pain, opioid withdrawal, and ADHD (extended-release form in some countries).
Also known as: Catapres
Ephedrine (indirect sympathomimetic) plus clonidine (central α2 agonist) can produce unpredictable pressor and sedative responses.
Clonidine reduces central sympathetic tone and noradrenaline release; ephedrine depends on that release — the pressor effect of ephedrine may be blunted, and clonidine withdrawal causes rebound hypertension.
Peri-operative blood pressure, sedation, heart rate.
Rebound hypertension, headache, agitation, tachycardia.
Never stop clonidine abruptly (rebound); peri-operatively continue clonidine and monitor blood pressure; titrate vasopressors with monitoring.
DailyMed — Ephedrine Sulfate Tablet label (adrenergics): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=e338deef-efad-1d82-e053-2995a90a1bf9; Clonidine HCl Tablet label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=d90b2ca4-7753-4012-a1b2-fb92bdf0ebb6
Clonidine potentiates propofol sedation and hypotension, reducing anaesthetic requirements but increasing haemodynamic instability risk.
Central α2 agonist: additive sedation and blunting of the sympathetic response to intubation (labels: reduce anaesthetics in α2-agonist patients).
Blood pressure, heart rate, anaesthetic depth.
Prolonged hypotension, bradycardia, need for vasopressors.
Reduce the propofol induction dose; monitor blood pressure and heart rate; never stop clonidine abruptly pre-operatively.
DailyMed — Diprivan (propofol) and Clonidine HCl Tablet labels: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=5ec25932-6c21-4cd5-8f60-80761f2e20a6
Alcohol potentiates clonidine sedation and hypotension — risk of dizziness, falls and excessive drowsiness.
Avoid alcohol, especially at treatment start and when standing up.
EMC-UK — Clonidine SmPC 4.4/4.5 (alcohol); site monograph.
Clonidine lowers heart rate — contraindicated in sick sinus syndrome and conduction blocks.
ECG before starting in cardiac patients; monitor for bradycardia.
Site monograph (clonidine — bradycardia, sick sinus); EMC-UK clonidine SmPC 4.3.
Clonidine may cause/worsen depression (central alpha-2 effect).
Monitor mood in patients with depressive history.
EMC-UK — clonidine SmPC 4.4/4.8 (depression).
No specific Annex 1 entry; clonidine is used as a regional anaesthesia adjunct and for hypertension. Pregnancy safety data are limited; some studies associate 3rd-trimester use with transient neonatal hypotension and bradycardia. If the mother is on chronic treatment, do not stop abruptly (rebound hypertensive crisis risk).
Use only if benefit justifies (already established chronic treatment, anaesthetic adjunct); never stop abruptly; monitor newborn bradycardia/hypotension.
Annex 2 records "Present in milk; the manufacturer recommends avoiding" (l. 42368).
Prontuário Terapêutico INFARMED — Annex 2: "Clonidine — Present in milk; the manufacturer recommends avoiding" (l. 42368). EMC-UK (MHRA) — Clonidine SmPC.
Clinical and educational support tool. The information does not replace a medical prescription or the opinion of a qualified healthcare professional.
Reduced blood pressure and heart rate; sedation and spinal analgesia.
Central alpha-2A agonist: reduces sympathetic outflow from the bulbar vasomotor centre; in the spinal cord, inhibits substance P and glutamate release (analgesia).
Oral: ~ 75–95% bioavailability; transdermal patch: 7-day release.
Hepatic hydroxylation (CYP2D6) and conjugation; ~ 65% excreted unchanged in urine.
~ 12–16 h (patch: ~ 20 h).
Medicines from the same therapeutic group (ATC classification) or the same pharmacological class.
