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clonidine (Catapres, Onyda XR)

Tradename: Catapres. (clonidine hydrochloride) Indications: - 2nd line treatment of mild to moderate hypertension - 2nd line therapy for hypertension - opiate withdrawal, heroin withdrawal - alcohol withdrawal - migraine prophylaxis - glaucoma - paralytic ileus - diabetes-associated diarrhea - atrial fibrillation - smoking cessation - muscle spasms & as adjunct to opiates in management of pain - attention-deficit hyperactivity disorder (ADHD) [7] - hot flashes associated with menopause Contraindications: - drug abuse - addicts may use clonidine to diminish withdrawals or to augment effects of illicit drugs [6] Dosage: - start 0.1 mg PO BID, max 2.4 mg/day. - Onyda XR for ADHD once a day Tabs: 0.1, 0.2. 0.3 mg. Transdermal (Catepres-TTS) 1 patch weekly. Patches: 0.1, 0.2, 0.3 mg/day. Hypertensive urgency: 1) 0.2 mg PO loading dose, then 0.1 mg hourly up to 0.6 mg. 2) Na+ retention occurs, thus a single dose of a diuretic is frequently used after clonidine loading. Pharmacokinetics: 1) onset of action after oral dose: 30-60 minutes 2) bioavailablity 75-95% 3) 20-40% bound to plasma proteins 4) metabolized in liver 5) 62% of drug excreted unchanged into the urine 6) elimination 1/2life is 7 hours 7) transdermal patch a) maximum reduction of heart rate in 3-4 hours b) constant effect over 7 day period c) elimination 1/2life is 14-26 hours [3] Adverse effects: 1) common (> 10%) - dry mouth - drowsiness - dizziness - constipation 2) less common (1-10%) - nausea/vomiting, increased serum transaminases, nervousness, agitation, depression, headache, orthostatic hypotension, rash, weakness, impotence, loss of libido, nocturia 3) uncommon (< 1%) - weight gain, gynecomastia, insomnia, vivid dreams, delirium, palpitations, tachycardia, bradycardia, Raynaud's phenomenon, congestive heart failure, pruritus, hives, urticaria, alopecia, difficulty in micturition, urinary retention, burning of the eyes, blurred vision, fever 4) rebound hypertension with clonidine withdrawal - taper over 2-4 days 5) topical - allergic contact dermatitis from transdermal delivery system [8] Drug interactions: 1) tricyclic antidepressants antagonize hypotensive effects of clonidine 2) beta-blockers a) may potentiate bradycardia b) may increase rebound hypertension seen with clonidine withdrawal c) discontinue beta blocker several days before clonidine is tapered 3) decreased effectiveness of L-dopa 4) prazosin decreases effectiveness of clonidine 5) verapamil a) synergistic pharmacologic & toxic effects b) AV block & severe hypotension 6) naloxone blocks central actions of clonidine Laboratory: 1) specimen: serum, plasma (heparin, EDTA) 2) methods: GC-MS, GLC, RIA Mechanism of action: 1) central alpha-2 adrenergic receptor agonist 2) decreases sympathetic outflow 3) initial stimulation of peripheral alpha adrenergic receptors 4) peripheral alpha adrenergic agonist & antagonist effects 5) diminishes vasomotor tone & heart rate

Interactions

drug interactions drug adverse effects (more general classes)

Related

apraclonidine

General

alpha-2 adrenergic receptor agonist centrally-active alpha-adrenergic receptor agonist imidazole; glyoxaline; 1,3-diazole; iminazole

Properties

AGONIST-FOR: alpha-2 adrenergic receptor MISC-INFO: elimination route KIDNEY LIVER onset-of-action 30-60 MIN 1/2life 5-23 HOURS therapeutic-range 1.0-2.0 NG/ML protein-binding 20-40% elimination by hemodialysis - pregnancy-category C safety in lactation ?

Database Correlations

PUBCHEM correlations

References

  1. The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
  2. Kaiser Permanente Northern California Regional Drug Formulary, 1998
  3. Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998
  4. Clinical Guide to Laboratory Tests, 3rd ed. Teitz ed., W.B. Saunders, 1995
  5. Geriatric Dosage Handbook, 6th edition, Selma et al eds, Lexi-Comp, Cleveland, 2001
  6. Prescriber's Letter 17(3): 2010 Clonidine Abuse Detail-Document#: 260305 (subscription needed) http://www.prescribersletter.com
  7. Deprecated Reference
  8. Corazza M, Mantovani L, Virgili A, Strumia R. Allergic contact dermatitis from a clonidine transdermal delivery system. Contact Dermatitis. 1995 Apr;32(4):246. PMID: 7600788

Component-of

chlorthalidone/clonidine (Combipres)