Epidural Chronic pain due to malignant neoplastic disease
Adult: In combination with opiates in severe cases: Initially, 30 mcg/hour via continuous infusion, adjusted according to response.
Intravenous Hypertensive crisis
Adult: 150-300 mcg given via slow inj over 10-15 minutes, dose may be repeated up to Max 750 mg over 24 hours.
Oral Attention deficit hyperactivity disorder
Child: 6-17 years As monotherapy or as adjunctive therapy to psychostimulant: As extended-release tab: Initially, 100 mcg at bedtime, increase by 100 mcg/day in weekly increments until desired response. Doses are given bid with either an equal or higher split dose given at bedtime. Max: 400 mcg daily. When discontinuing, taper dose in decrements of not more than 100 mcg every 3-7 days.
Oral Menopausal flushing, Prophylaxis of migraine, Vascular headache, prophylaxis
Adult: Initially, 50 mcg bid, increased to 75 mcg bid if no remission after 2 weeks.
Oral Hypertension
Adult: Initially, 50-100 mcg tid, gradually increased every 2nd or 3rd day according to response. Maintenance: 300-1,200 mcg daily in divided doses. Alternatively, 100 mcg bid, increase in increments of 100 mcg/day at weekly intervals until desired response is achieved. Max: 2.4 mg daily.
Transdermal Hypertension
Adult: As patch: Initially, 100 mg/24 hour patch applied once weekly on upper outer arm or chest, may increase to 200-300 mg/24 hour patch once weekly according to response.
Renal Impairment
Dosage adjustment is necessary.
Administration
May be taken with or without food.
Reconstitution
Epidural: Dilute vial labelled as containing 500 mcg/mL with 0.9% NaCl for inj to a final concentration of 100 mcg/mL.
Contraindications
Severe bradyarrhythmia secondary to 2nd- or 3rd-degree AV block or sick sinus syndrome. Epidural administration: Inj site infection, concomitant anticoagulant therapy, bleeding diathesis, administration above the C4 dermatome.
Special Precautions
Patient with CV disease (e.g. severe coronary insufficiency, recent MI, conduction disturbances including sinus node dysfunction), haemodynamic instability; cerebrovascular disease; occlusive peripheral vascular disorders (e.g. Raynaud’s disease), pre-existing or risk factors for bradycardia; pre-existing or history of depression. Avoid abrupt withdrawal. Renal impairment. Children. Pregnancy and lactation.
Adverse Reactions
Significant: Hypotension, bradycardia, CNS depression, respiratory depression (epidural), xerostomia, skin rash (transdermal). Cardiac disorders: Sinus bradycardia. Gastrointestinal disorders: Constipation, nausea, salivary gland pain, vomiting. General disorders and administration site conditions: Fatigue, malaise. Nervous system disorders: Drowsiness, dizziness, sedation, headache, paraesthesia. Psychiatric disorders: Sleep disorder, depression, hallucination, delusional perception, nightmare. Reproductive system and breast disorders: Erectile dysfunction. Skin and subcutaneous tissue disorders: Pruritus, rash, urticaria. Vascular disorders: Orthostatic hypotension (1st dose), Raynaud’s phenomenon.
This drug may cause drowsiness, dizziness, if affected, do not drive or operate machinery.
Monitoring Parameters
Monitor blood pressure (standing and sitting/supine positions), heart rate and mental status. Epidural: Monitor for catheter-related infection (e.g. meningitis or epidural abscess).
Overdosage
Symptoms: Generalised sympathetic depression including pupillary constriction, lethargy, bradycardia, hypotension, hypothermia, drowsiness, somnolence, coma, respiratory depression apnoea, paradoxical hypertension, decreased or absent reflexes, weakness, irritability, miosis. Management: Supportive treatment. Perform gastric lavage following recent or large ingestions or administer activated charcoal and/or a cathartic. May administer atropine sulfate for bradycardia; IV fluids and/or vasopressor agents for hypotension; and vasodilators for hypertension. Naloxone may be used as adjunct for clonidine-induced respiratory depression, hypotension and/or coma with blood pressure monitoring.
Drug Interactions
Increased hypotensive effect with narcotic analgesic and other antihypertensive agents (e.g. diuretics, β-blockers, vasodilators, Ca antagonists, ACE inhibitors). May potentiate CNS depressant effect of barbiturates or other sedating drugs. Reduced antihypertensive effect and induced orthostatic hypotension with TCAs or neuroleptics with α-receptor blocking properties. Diminished antihypertensive effect with mirtazapine. May potentiate AV-blocking effect of cardiac glycosides. May increase arrhythmogenic potential (e.g. QT prolongation, ventricular fibrillation) of high doses of IV haloperidol. Potentially Fatal: May cause sudden death with methylphenidate.
Food Interaction
May potentiate CNS depressant effect of alcohol.
Lab Interference
Weakly positive Coomb’s test. May lead to false-positive aldosterone/renin ratio.
Action
Description: Mechanism of Action: Clonidine stimulates α2-adrenoceptors in the brain stem which results in reduced sympathetic tone and decreased peripheral resistance, renal vascular resistance, heart rate and blood pressure. Onset: Antihypertensive effect: Immediate-release: 0.5-1 hour; 2-4 hours (maximum reduction in blood pressure). Transdermal: 2-3 days (initial); approx 3 days (steady state). Pharmacokinetics: Absorption: Well-absorbed from the gastrointestinal tract. Bioavailability: 70-80% (immediate-release); approx 89% (extended release); approx 60% (transdermal). Time to peak plasma concentration: 1-3 hours (immediate-release); 7-8 hours (extended-release). Distribution: Crosses placenta, enters the breast milk and distributes readily into extravascular sites. Volume of distribution: Approx 2.9 L/kg. Plasma protein binding: 20-40% Metabolism: Metabolised in the liver to inactive metabolites; undergoes enterohepatic recirculation. Excretion: Via urine (40-60% as unchanged drug); faeces (approx 20%). Elimination half-life: 12-16 hours; 22 ±15 hours (epidural); approx 20 hours (transdermal).
Chemical Structure
Clonidine Source: National Center for Biotechnology Information. PubChem Database. Clonidine, CID=2803, https://pubchem.ncbi.nlm.nih.gov/compound/Clonidine (accessed on Jan. 21, 2020)
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
Anon. Clonidine. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 21/02/2020.Anon. Clonidine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 10/09/2019.Boehringer Ingelheim International GmbH. Catapres-TTS data sheet 1 February 2019. Medsafe. Medsafe. http://www.medsafe.govt.nz/. Accessed 10/09/2019.Buckingham R (ed). Clonidine. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 10/09/2019.Clonidine Hydrochloride Injection, Solution (West-Ward Pharmaceuticals Corp). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 10/09/2019.Clonidine Hydrochloride Tablet (Alembic Pharmaceuticals Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 10/09/2019.Joint Formulary Committee. Clonidine Hydrochloride. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 10/09/2019.Kapvay Tablet, Extended Release (Concordia Pharmaceuticals Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 20/02/2020.
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