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Pronunciation |
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(KLOE
ni
deen) |

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U.S. Brand
Names |
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Catapres® Oral; Catapres-TTS®
Transdermal; Duraclon®
Injection |

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Generic
Available |
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Yes: Tablet |

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Canadian Brand
Names |
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Apo®-Clonidine; Dixarit®;
Novo-Clonidine; Nu-Clonidine |

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Synonyms |
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Clonidine Hydrochloride |

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Pharmacological Index |
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Alpha2 Agonist |

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Use |
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Management of mild to moderate hypertension; either used alone or in
combination with other antihypertensives |

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Pregnancy Risk
Factor |
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C |

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Pregnancy/Breast-Feeding
Implications |
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Clinical effects on the fetus: Crosses the placenta. Caution should be used
with this drug due to the potential of rebound hypertension with abrupt
discontinuation.
Breast-feeding/lactation: Crosses into breast milk. American Academy of
Pediatrics has NO RECOMMENDATION. |

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Contraindications |
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Hypersensitivity to clonidine hydrochloride or any
component |

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Warnings/Precautions |
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Gradual withdrawal is needed (over 1 week for oral, 2-4 days with epidural)
if drug needs to be stopped. Patients should be instructed about abrupt
discontinuation (causes rapid increase in BP and symptoms of sympathetic
overactivity). In patients on both a beta-blocker and clonidine where withdrawal
of clonidine is necessary, withdraw the beta-blocker first and several days
before clonidine. Then slowly decrease clonidine. |

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Adverse
Reactions |
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Incidence of adverse events is not always reported.
Central nervous system: Drowsiness (35% oral, 12% transdermal), dizziness
(16% oral, 2% transdermal)
Dermatologic: Transient localized skin reactions characterized by pruritus,
and erythema (15% to 50% transdermal)
Gastrointestinal: Dry mouth (40% oral, 25% transdermal)
1% to 10%:
Cardiovascular: Orthostatic hypotension (3% oral)
Central nervous system: Headache (1% oral, 5% transdermal), sedation (3%
transdermal), fatigue (6% transdermal), lethargy (3% transdermal), insomnia (2%
transdermal), nervousness (3% oral, 1% transdermal), mental depression (1% oral)
Dermatologic: Rash (1% oral), allergic contact sensitivity (5% transdermal),
localized vesiculation (7%), hyperpigmentation (5% at application site), edema
(3%), excoriation (3%), burning (3%), throbbing, blanching (1%), papules (1%),
and generalized macular rash (1%) has occurred in patients receiving transdermal
clonidine.
Endocrine & metabolic: Sodium and water retention, sexual dysfunction (3%
oral, 2% transdermal), impotence (3% oral, 2% transdermal), weakness (10%
transdermal)
Gastrointestinal: Nausea (5% oral, 1% transdermal), vomiting (5% oral),
anorexia and malaise (1% oral), constipation (10% oral, 1% transdermal), dry
throat (2% transdermal), taste disturbance (1% transdermal), weight gain (1%
oral)
Genitourinary: Nocturia (1% oral)
Hepatic: Liver function test (mild abnormalities, 1% oral)
Miscellaneous: Withdrawal syndrome (1% oral)
<1% (Limited to important or life-threatening symptoms): Hepatitis (oral),
difficulty in micturition (oral, transdermal), urinary retention (oral), hives
(oral, transdermal), angioedema (oral, transdermal), urticaria (oral,
transdermal), alopecia (oral, transdermal), parotid pain (oral), gynecomastia
(oral, transdermal), transient elevation of blood glucose (oral), elevation of
creatinine phosphokinase (oral), palpitations (oral, transdermal), tachycardia
(oral, transdermal), bradycardia (oral), sinus bradycardia (oral, transdermal),
atrioventricular block (oral, transdermal), congestive heart failure (oral,
transdermal), EKG abnormalities (oral, transdermal), flushing, pallor, Raynaud's
phenomenon (oral, transdermal), chest pain (transdermal), increase in blood
pressure (transdermal), weakness, muscle or joint pain (0.6% oral), leg cramps
(0.3% oral), fever (oral, transdermal), malaise (transdermal), withdrawal
syndrome (transdermal), vivid dreams (oral, transdermal), nightmares (oral,
transdermal), insomnia (oral), behavioral changes (transdermal), restlessness
(oral, transdermal), anxiety (oral, transdermal), mental depression
(transdermal), visual and auditory hallucinations (oral, transdermal), delirium
(transdermal), CVA (transdermal), irritability (transdermal), weight gain
(transdermal), rash (transdermal), orthostatic symptoms (transdermal), syncope
(oral, transdermal), agitation (transdermal), contact dermatitis (transdermal),
localized hypo or hyperpigmentation (transdermal), anorexia (transdermal),
anorexia (transdermal), vomiting (transdermal), vomiting (transdermal), loss of
libido (transdermal), decreased sexual activity (transdermal), blurred vision
(transdermal), burning of the eyes (transdermal), dryness of the eyes
(transdermal), weakly positive Coombs' test (oral), increased sensitivity to
alcohol (oral), palpitations (oral), tachycardia (oral), thrombocytopenia
(oral), abdominal pain (oral), pseudo-obstruction (oral) |

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Overdosage/Toxicology |
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Symptoms of overdose include bradycardia, CNS depression, hypothermia,
diarrhea, respiratory depression, apnea
Treatment is primarily supportive and symptomatic. Hypotension usually
responds to I.V. fluids or Trendelenburg positioning. Naloxone may be utilized
in treating CNS depression and/or apnea and should be given I.V. 0.4-2 mg, with
repeated doses as needed or as an infusion. |

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Drug
Interactions |
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CNS depressants: Effects may be additive.
Concurrent use with antipsychotics (especially low potency) or nitroprusside
may produce additive hypotensive effects.
Clonidine may decrease the symptoms of hypoglycemia; monitor patients
receiving antidiabetic agents.
Cyclosporine (and perhaps tacrolimus) serum concentrations may increase.
Monitor cyclosporine serum concentrations; dosage adjustment may be needed.
TCAs antagonize hypotensive effects of clonidine; best to avoid this
combination; consider an alternative agent.
Beta-blockers may potentiate bradycardia in patients receiving clonidine and
may increase the rebound hypertension of withdrawal; discontinue beta-blocker
several days before clonidine is tapered.
Narcotic analgesics may potentiate hypotensive effects of clonidine.
Alcohol and barbiturates may increase the CNS depression; epidural clonidine
may prolong the sensory and motor blockade of local anesthetics.
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Mechanism of
Action |
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Stimulates alpha2-adrenoceptors in the brain stem, thus activating
an inhibitory neuron, resulting in reduced sympathetic outflow from the CNS,
producing a decrease in peripheral resistance, renal vascular resistance, heart
rate, and blood pressure; epidural clonidine may produce pain relief at spinal
presynaptic and postjunctional alpha2-adrenoceptors by preventing
pain signal transmission; pain relief occurs only for the body regions
innervated by the spinal segments where analgesic concentrations of clonidine
exist |

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Pharmacodynamics/Kinetics |
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Onset of effect: Oral: 0.5-1 hour; Tmax: 2-4 hours
Duration: 6-10 hours
Distribution: Vd: 2.1 L/kg (adults); highly lipid soluble;
distributes readily into extravascular sites; protein binding: 20% to 40%
Metabolism: Hepatic (enterohepatic recirculation); extensively metabolized to
inactive metabolites
Bioavailability: 75% to 95%
Half-life: Adults: Normal renal function: 6-20 hours; Renal impairment: 18-41
hours
Elimination: 65% excreted in urine, 32% unchanged, and 22% excreted in feces;
not removed significantly by hemodialysis |

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Usual Dosage |
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Oral:
Children: Initial: 5-10 mcg/kg/day in divided doses every 8-12 hours;
increase gradually at 5- to 7-day intervals to 25 mcg/kg/day in divided doses
every 6 hours; maximum: 0.9 mg/day
Clonidine tolerance test (test of growth hormone release from pituitary):
0.15 mg/m2 or 4 mcg/kg as single dose
Adults: Initial dose: 0.1 mg twice daily, usual maintenance dose: 0.2-1.2
mg/day in 2-4 divided doses; maximum recommended dose: 2.4 mg/day
Nicotine withdrawal symptoms: 0.1 mg twice daily to maximum of 0.4 mg/day for
3-4 weeks
Elderly: Initial: 0.1 mg once daily at bedtime, increase gradually as needed.
Transdermal: Apply once every 7 days; for initial therapy start with 0.1 mg
and increase by 0.1 mg at 1- to 2-week intervals; dosages >0.6 mg do not
improve efficacy.
Epidural infusion: Starting dose: 30 mcg/hour; titrate as required for relief
of pain or presence of side effects; minimal experience with doses >40
mcg/hour; should be considered an adjunct to intraspinal opiate therapy.
Dosing adjustment in renal impairment: Clcr <10
mL/minute: Administer 50% to 75% of normal dose initially.
Dialysis: Not dialyzable (0% to 5%) via hemo- or peritoneal dialysis;
supplemental dose not necessary. |

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Dietary
Considerations |
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Hypertensive patients may need to decrease sodium and calories in
diet |

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Monitoring
Parameters |
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Blood pressure, standing and sitting/supine, respiratory rate and depth, pain
relief, mental status, heart rate (bradycardia may be treated with
atropine) |

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Reference Range |
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Therapeutic: 1-2 ng/mL (SI: 4.4-8.7 nmol/L) |

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Test
Interactions |
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sodium (S);
catecholamines (U)
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Cardiovascular
Considerations |
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Tolerance to the blood pressure lowering effects of clonidine may develop
with long-term therapy. Abrupt withdrawal from clonidine therapy should be very
specifically avoided. The advent of the clonidine patch has provided an
important alternative to frequent daily dosing. However, it is important that
overlap of therapy be maintained when switching from oral medications to the
patch. Important side effects of clonidine include drowsiness. It has also been
suggested that clonidine may be useful in promoting smoking cessation.
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Mental Health: Effects
on Mental Status |
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Drowsiness is common |

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Mental Health:
Effects on Psychiatric
Treatment |
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Dry mouth, orthostatic hypotension, and sedation may be increased with
concurrent psychotropic use; used to treat clozapine-induced sialorrhea; TCAs
may antagonize clonidine's hypotensive effect |

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Dental Health: Local
Anesthetic/Vasoconstrictor
Precautions |
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No information available to require special precautions |

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Dental Health:
Effects on Dental Treatment |
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>10% of patients experience significant dry mouth |

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Patient
Information |
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Take as directed, at bedtime. Do not skip doses or discontinue without
consulting prescriber. If using patch, check daily for correct placement. Do not
use OTC medications which may affect blood pressure (eg, cough or cold remedies,
diet pills, stay-awake medications) without consulting prescriber. This
medication may cause drowsiness, dizziness, or impaired judgment (use caution
when driving or engaging in tasks that require alertness until response is
known); decreased libido or sexual function (will resolve when drug is
discontinued); postural hypotension (use caution when rising from sitting or
lying position or when climbing stairs); constipation (increase roughage, bulk
in diet); or dry mouth or nausea (frequent mouth care or sucking lozenges may
help). Report difficulty, pain, or burning on urination; increased nervousness
or depression; sudden weight gain (weigh yourself in the same clothes at the
same time of day once a week); unusual or persistent swelling of ankles, feet,
or extremities; wet cough or respiratory difficulty; chest pain or palpitations;
muscle weakness, fatigue, or pain; or other persistent side effects.
Pregnancy/breast-feeding precautions: Inform prescriber if you are or intend
to be pregnant. Breast-feeding is not recommended. |

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Nursing
Implications |
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Patches should be applied weekly at bedtime to a clean, hairless area of the
upper outer arm or chest; rotate patch sites weekly; redness under patch may be
reduced if a topical corticosteroid spray is applied to the area before
placement of the patch; if needed, gradually reduce dose over 2-4 days to avoid
rebound hypertension; during epidural administration, monitor cardiovascular and
respiratory status carefully |

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Dosage Forms |
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Injection, preservative free, as hydrochloride: 100 mcg/mL (10 mL)
Patch, transdermal, as hydrochloride: 1, 2, and 3 (0.1, 0.2, 0.3 mg/day,
7-day duration)
Tablet, as hydrochloride: 0.1 mg, 0.2 mg, 0.3 mg |

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References |
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Capogna G, Celleno D, Zangrillo A, et al,
"Addition of Clonidine to Epidural Morphine Enhances Postoperative Analgesia After Cesarean Delivery,"
Reg Anesth, 1995, 20(1):57-61.
Corazza M, Mantovani L, Virgili A, et al,
"Allergic Contact Dermatitis From a Clonidine Transdermal Delivery System,"
Contact Dermatitis, 1995, 32(4):246.
Fizer DH, Moss MN, and Walker W,
"Critical Care for Clonidine Poisoning in Toddlers," Crit Care Med, 1990,
18(10):1124-8.
Fowler MA, Wheeler CA, and Wasserman GS,
"Case 01-1995: A Two Year Old Female With Alteration of Consciousness,"
Pediatr Emerg Care, 1995, 11(1):62.
Hart-Santora D and Hart LL,
"Clonidine in Attention Deficit Hyperactivity Disorder," Ann
Pharmacother, 1992, 26(1):37-9.
Hunt RD, Minderaa RB, and Cohen DJ,
"The Therapeutic Effect of Clonidine in Attention Deficit Disorder With Hyperactivity: A Comparison With Placebo and Methylphenidate,"
Psychopharmacol Bull, 1986, 22(1):229-35.
Klein MD, "An Unusual Cause of Clonidine Toxicity," Am J Emerg Med,
1991, 9(4):409-10.
Kulig K, Duffy JP, Rumack BH, et al,
"Naloxone for the Treatment of Clonidine Overdose," JAMA, 1982,
247(12):1697.
Rocchini AP, "Childhood Hypertension: Etiology, Diagnosis, and Treatment,"
Pediatr Clin North Am, 1984, 31(6):1259-73.
Sinaiko AR, "Pharmacologic Management of Childhood Hypertension," Pediatr
Clin North Am, 1993, 40(1):195-212. |

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