clonidine (Catapres)

see also:

• antihypertensives

• Centrally acting alpha 2 adrenergic agonist
• Appears to reduce neurally mediated plasma catecholamine levels
• Primarily used as an antihypertensive but has also been used to Rx:
  • has been used to prevent migraine attacks in 75-150mcg daily doses but less effective than other preventives, although it appears to have 30-50% of patients who have a 50% or more reduction in headache frequency
  • post-operative agitation and pain
  • opiate withdrawal
  • benzodiazepine withdrawal
  • alcohol withdrawal
  • nicotine withdrawal
  • attention deficit hyperactivity disorder (ADHD)
  • Tourette syndrome
  • hot flushes of menopause
  • hyperarousal caused by post-traumatic stress disorder, borderline personality disorder, and other anxiety disorders
  • restless legs syndrome
  • has been successfully used topically in a clinical trial as a treatment for diabetic neuropathy
  • has been used to treat diarrhoea associated with irritable bowel syndrome, fecal incontinence, diabetes, withdrawal-associated diarrhea, intestinal failure, neuroendocrine tumors and cholera
  • marine stings such as Irukandji syndrome

• Severe bradyarrhythmia due to sick sinus syndrome
• 2nd or 3rd degree A-V block
• oral tablet form: hereditary galactose intolerance eg galactosaemia

• abrupt withdrawal (esp with prolonged use, high dose) may cause restlessness, palpitations, rapid rise in blood pressure, nervousness, tremor, headache or nausea. Wean over 7 days if possible.
• depression history;
• advanced cerebrovascular disease
• hepatic, renal impairment
• diabetes
• mild-mod bradyarrhythmia
• perfusion disorder
• polyneuropathy
• constipation
• congestive cardiac failure or severe coronary disease
• hypertension due to phaeochromocytoma - as no Rx effect in this situation
• beta-blocker withdrawal
• ophthalmological monitoring, contact lens use
• surgery (anaesthesia)
• pregnancy (cat B3 - in some circumstances the incidence of embryonic and perinatal deaths was increased )
• lactation (excreted in human milk, should not use)
• children, adolescents (not recommended esp with ADHD and concomitant methylphenidate)

• sinus bradycardia
• orthostatic hypotension
• Raynaud's phenomenon
• drowsiness, dry mouth, constipation, nausea, salivary gland pain, vomiting
• uncommonly, allergic reaction, erectile dysfunction, fatigue, dry eyes, dry nose, headache, depression, sleep disorder, delusional perception, hallucination, nightmare
• rarely, AV block, alopecia, hepatitis, paraesthesiae, gynaecomastia, colonic pseudo-obstruction

• Initially: 75 mcg 2-3 times daily; incr daily dose by 75 mcg increments according to response; max 900 mcg/day.
• Maintenance: 150-300 mcg 3 times daily

• Admin by SCI, IMI (undiluted, with patient in recumbent position) or IVI (in normal saline 10 mL over 5 min)
• 150-300 mcg; may repeat at 3-6 hr intervals
  • Renal, hepatic impairment: may require dose reduction, but for dialysis patients, only a minimal amount of clonidine is removed during routine haemodialysis, thus there is no need to give supplemental clonidine following dialysis
  • Following intravenous injection an initial pressor phase of 5-10 mmHg lasting approximately 5 minutes may occur. This can be avoided by giving a slower rate.