Adult: As an adjunctive treatment with opioids in patients who are unresponsive or tolerant to opioids alone: Initially, 30 mcg/hour via continuous epidural infusion. Adjust dose according to patient response and tolerance. Treatment recommendations may vary among countries and between individual products (refer to local or specific product guidelines).
Intramuscular, Intravenous Hypertensive crisis
Adult: 150-300 mcg via slow IV inj over 10-15 minutes or IM inj; may be repeated at intervals of 3-6 hours as needed. Max: 750 mcg per 24 hours. Treatment recommendations may vary among countries and between individual products (refer to local or specific product guidelines).
Oral Menopausal flushing, Prophylaxis of migraine, Prophylaxis of recurrent vascular headache
Adult: As conventional tab or oral solution: Initially, 50 mcg bid; may increase to 75 mcg bid if there is no remission after 2 weeks. Treatment duration depends on the severity of the condition. Dosage and treatment recommendations may vary among countries and between individual products (refer to local or specific product guidelines).
Oral Attention deficit hyperactivity disorder
Child: ≥6 years Monotherapy or adjunctive treatment to CNS stimulants: As extended-release oral susp: Initially, 100 mcg once daily at bedtime; may titrate dose in 100 mcg per day increments at weekly intervals according to clinical response. Max: 400 mcg once daily at bedtime. As extended-release tab: Initially, 100 mcg at bedtime; adjust dose in 100 mcg per day increments at weekly intervals until the desired response is achieved. Max: 400 mcg daily. Doses of the extended-release tab are given bid after the initial dose, either equally divided or the higher split dosage given at bedtime.
Oral Hypertension
Adult: Monotherapy or in combination with other antihypertensive agents: As conventional tab: Initially, 50-100 mcg tid; may be increased gradually every 2nd or 3rd day according to patient response. Usual maintenance dose: 300-1,200 mcg daily. Alternatively, give an initial dose of 100 mcg bid; may be increased in 100 mcg per day increments at weekly intervals until the desired response is achieved. Usual dose range: 200-600 mcg daily in 2 or 3 divided doses. As extended-release tab (Nexiclon XR): Initially, 170 mcg once daily at bedtime; may be increased in 90 mcg per day increments at weekly intervals until the desired response is achieved. Usual dose range: 170-520 mcg once daily. Dosage recommendations may vary among countries and between individual products (refer to local or specific product guidelines).
Transdermal Hypertension
Adult: Monotherapy or in combination with other antihypertensive agents: As patch: Initially, apply 100 mcg/24-hour patch once every 7 days to a hairless area of intact skin on the upper outer arm or chest. Dose may be increased by 100 mcg after 1 or 2 weeks if the desired reduction in blood pressure is not achieved. Usual dose range: 100-300 mcg/24-hour patch applied once every 7 days.
Renal Impairment
Hypertension; Hypertensive crisis; Severe cancer pain:
Dose adjustment may be necessary.
Administration
Clonidine May be taken with or without food.
Reconstitution
IV inj: Dilute in 10 mL of NaCl 0.9% or dextrose 5% in water. Epidural infusion: Dilute vial labelled as 500 mcg/mL concentration in appropriate volume of NaCl 0.9% inj (preservative-free) to make a final concentration of 100 mcg/mL.
Contraindications
Severe bradyarrhythmia secondary to sick sinus syndrome or 2nd- or 3rd-degree AV block. Epidural: Bleeding diathesis, inj site infection; administration above the C4 dermatome; concomitant anticoagulant therapy.
Special Precautions
Patient with cerebrovascular disease, Raynaud's disease or other occlusive peripheral vascular disease; heart failure, severe coronary insufficiency (including recent MI), mild to moderate bradyarrhythmia (e.g. low sinus rhythm); constipation, polyneuropathy, history of depression. Avoid abrupt withdrawal. Epidural administration is not recommended for obstetrical, postpartum or perioperative pain management, and in patients with severe CV disease or haemodynamic instability. Oral drug preparations of clonidine may not be interchangeable due to different pharmacokinetic profiles; refer to the specific product guidelines for detailed information. Renal impairment. Children and elderly. Pregnancy and lactation. Concomitant use with methylphenidate (particularly in children with attention deficit hyperactivity disorder) is not recommended.
Adverse Reactions
Significant: Rebound hypertension or withdrawal syndrome (upon abrupt discontinuation); hypotension, bradycardia (dose-dependent); CNS depression, including sedation and somnolence. Eye disorders: Decreased lacrimation. Gastrointestinal disorders: Dry mouth, nausea, vomiting, constipation, salivary gland pain, upper abdominal pain, dysgeusia. General disorders and administration site conditions: Fatigue. Nervous system disorders: Headache, dizziness. Psychiatric disorders: Depression, sleep disorder, insomnia, nightmares, nervousness. Reproductive system and breast disorders: Erectile dysfunction. Skin and subcutaneous tissue disorders: Rash, pruritus, erythema, localised vesiculation, blanching, oedema, hyperpigmentation, skin excoriation, burning of the skin, papules (transdermal). Vascular disorders: Orthostatic hypotension.
This drug may cause drowsiness or dizziness, if affected, do not drive or operate machinery.
Monitoring Parameters
Monitor blood pressure, heart rate and mental status. For epidural use: Closely monitor the infusion pump, catheter tubing for obstruction or dislodgement, and assess for catheter-related infection (e.g. epidural abscess, meningitis).
Overdosage
Symptoms: Miosis, lethargy, bradycardia, profound hypotension, hypothermia, somnolence, seizures, transient hypertension, cardiac conduction defects or dysrhythmias, apnoea, coma, respiratory depression. Management: Supportive and symptomatic treatment. Perform gastric lavage following recent or large ingestions. Administer activated charcoal and/or a cathartic agent. May administer atropine sulfate for symptomatic bradycardia; IV fluids and/or inotropic sympathomimetic agents for hypotension; and vasodilators for hypertension. Naloxone may be used as an adjunct for clonidine-induced respiratory depression, hypotension and/or coma with blood pressure monitoring.
Drug Interactions
Concomitant use with β-blockers may exacerbate rebound hypertension caused by clonidine withdrawal. May potentiate hypotensive effect with other antihypertensive agents (e.g. diuretics, vasodilators, calcium channel blockers, ACE inhibitors). Concomitant use with drugs that affect sinus node function or AV node conduction (e.g. digitalis glycosides, β-blockers, calcium channel blockers) may potentiate bradycardic rhythm disturbances or risk of AV block. May reduce antihypertensive effect with NSAIDs and mirtazapine. Concomitant use with TCAs or neuroleptics with α-receptor blocking properties may induce orthostatic hypotension or may decrease the antihypertensive effect of clonidine. May potentiate the sedative effect of CNS depressants (e.g. barbiturates, opioids, anaesthetics). Potentially Fatal: Concomitant use with methylphenidate may cause severe adverse reactions.
Food Interaction
May potentiate the sedative effect of alcohol.
Lab Interference
May give positive Coombs' test. May result in false-positive aldosterone/renin ratio.
Action
Description: Mechanism of Action: Clonidine is an imidazoline-derivative hypotensive agent that stimulates α2-adrenoceptors in the brain, which activates an inhibitory neuron, resulting in decreased sympathetic outflow from the CNS and reduced peripheral resistance, renal vascular resistance, blood pressure, and heart rate. When administered epidurally, it prevents the transmission of pain signals to the brain, producing pain relief at the spinal presynaptic and postjunctional α2-adrenoceptors. Its exact mechanism of action for the treatment of attention deficit hyperactivity disorder is unknown; however, it is proposed that its stimulation of postsynaptic α2-adrenoceptors regulates subcortical activity in the prefrontal cortex, resulting in reduced hyperactivity, impulsiveness, and distractibility. Onset: Antihypertensive: Conventional oral forms: 0.5-1 hour. Transdermal: 2-3 days (initial use). Pharmacokinetics: Absorption: Well absorbed from the gastrointestinal tract; well absorbed through the skin (transdermal). Bioavailability: Conventional forms: 70-80%. Transdermal: Approx 60%. Time to peak plasma concentration: Conventional forms: 1-3 hours. Extended-release oral susp: 7.5 hours (range: 4-17 hours). Distribution: Rapidly and extensively distributed into tissues. Crosses the placenta and enters breast milk. Volume of distribution: Approx 2.9 L/kg. Plasma protein binding: Approx 20-40%. Metabolism: Extensively metabolised in the liver into inactive metabolites; undergoes enterohepatic recirculation. Excretion: Via urine (40-60% as unchanged drug); faeces (approx 20%). Elimination half-life: 12-16 hours. Epidural: 22 ± 15 hours (plasma). Transdermal: Approx 20 hours (after patch removal).
Chemical Structure
Clonidine Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 2803, Clonidine. https://pubchem.ncbi.nlm.nih.gov/compound/Clonidine. Accessed Aug. 26, 2025.
Storage
Conventional tab or oral solution/Extended-release tab or oral susp/IV inj/Transdermal patch: Store below 30°C. Epidural formulation: Store between 20-25°C. Storage recommendations may vary between individual products. Refer to specific product guidelines.
S01EA04 - clonidine ; Belongs to the class of sympathomimetics used in the treatment of glaucoma. N02CX02 - clonidine ; Belongs to the class of other antimigraine preparations. C02AC01 - clonidine ; Belongs to the class of imidazoline receptor agonists, centrally-acting antiadrenergic agents. Used in the treatment of hypertension.
References
Brayfield A, Cadart C (eds). Clonidine. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 04/08/2025.Catapres Ampoules 150 micrograms in 1 mL Solution for Injection (Glenwood GmbH). MHRA. https://products.mhra.gov.uk. Accessed 04/08/2025.Catapres Tablets 100 micrograms (Glenwood GmbH). MHRA. https://products.mhra.gov.uk. Accessed 04/08/2025.Catapres-TTS-1, 2, and 3 Transdermal System Patch (Technomed Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 04/08/2025.Clinect NZ Pty Limited. Catapres 150 mcg Tablets and 150 mcg/mL Solution for Injection data sheet 31 May 2023. Medsafe. http://www.medsafe.govt.nz. Accessed 04/08/2025.Clonidine Hydrochloride 25 mcg Tablets (Orbit Pharma Limited). MHRA. https://products.mhra.gov.uk. Accessed 04/08/2025.Clonidine Hydrochloride 50 micrograms/5 mL Oral Solution (Milpharm Limited). MHRA. https://products.mhra.gov.uk. Accessed 04/08/2025.Clonidine Hydrochloride Tablet (Alembic Pharmaceuticals Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 04/08/2025.Clonidine Hydrochloride Tablet, Extended Release (Somerset Therapeutics, LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 04/08/2025.Clonidine Injection, Solution (XGen Pharmaceuticals DJB, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 04/08/2025.Clonidine, Clonidine Hydrochloride. UpToDate Lexidrug, AHFS DI (Adult and Pediatric) Online. American Society of Health-System Pharmacists, Inc. Waltham, MA. UpToDate, Inc. https://online.lexi.com. Accessed 13/08/2025.Clonidine. UpToDate Lexidrug, Lexi-Drugs Multinational Online. Waltham, MA. UpToDate, Inc. https://online.lexi.com. Accessed 04/08/2025.Joint Formulary Committee. Clonidine Hydrochloride. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 04/08/2025.Nexiclon XR Tablet, Extended Release (Athena Bioscience, LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 13/08/2025.Onyda XR Suspension, Extended Release (NextWave Pharmaceuticals, Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 04/08/2025.Viatris Ltd. Clonidine Transdermal System, USP Transdermal Patch data sheet 15 March 2022. Medsafe. http://www.medsafe.govt.nz. Accessed 04/08/2025.YSP Clonidine Injection 150 mcg/mL (Y.S.P. Industries [M] Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 04/08/2025.
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