Clonidine hydrochloride

clonidine hydrochloride

(kloe' ni deen)

Antihypertensives:

Apo-Clonidine (CAN), Catapres, Catapres-TTS (transdermal preparation), Dixarit (CAN), Duraclon, Novo-Clonidine (CAN), Nu-Clonidine (CAN)

Analgesic:

Duraclon

Pregnancy Category C

Drug classes

Antihypertensive

Sympatholytic (centrally acting)

Central analgesic

Therapeutic actions

Stimulates CNS alpha₂-adrenergic receptors, inhibits sympathetic cardioaccelerator and vasoconstrictor centers, and decreases sympathetic outflow from the CNS.

Indications

·        Hypertension, used alone or as part of combination therapy

·        Treatment of severe pain in cancer patients in combination with opiates; epidural more effective with neuropathic pain (Duraclon)

·        Unlabeled uses: Tourette's syndrome; migraine, decreases severity and frequency; menopausal flushing, decreases severity and frequency of episodes; chronic methadone detoxification; rapid opiate detoxification (in doses up to 17 mcg/kg/day); alcohol and benzodiazepine withdrawal treatment; management of hypertensive "urgencies"; (oral clonidine "loading" is used; initial dose of 0.2 mg then 0.1 mg every hour until a dose of 0.7 mg is reached or until BP is controlled)

Contraindications and cautions

·        Contraindicated with hypersensitivity to clonidine or any adhesive layer components of the transdermal system.

·        Use cautiously with severe coronary insufficiency, recent MI, cerebrovascular disease; chronic renal failure; pregnancy, lactation.

Available forms

Tablets—0.1, 0.2, 0.3 mg; transdermal—0.1, 0.2, 0.3 mg/24 hr; epidural injection—100 mcg/mL

Dosages

ADULTS

Oral therapy

Individualize dosage. Initial dose is 0.1 mg bid; for maintenance dosage, increase in increments of 0.1 or 0.2 mg to reach desired response. Common range is 0.2–0.6 mg/day, in divided doses; maximum dose is 2.4 mg/day. Minimize sedation by slowly increasing daily dosage; giving majority of daily dose hs.

Transdermal system

Apply to a hairless area of intact skin of upper arm or torso once every 7 days. Change skin site for each application. If system loosens while wearing, apply adhesive overlay directly over the system to ensure adhesion. Start with the 0.1-mg system (releases 0.1 mg/24 hr); if, after 1–2 wk, desired BP reduction is not achieved, add another 0.1-mg system, or use a larger system. Dosage of more than two 0.3-mg systems does not improve efficacy. Antihypertensive effect may only begin 2–3 days after application; therefore, when substituting transdermal systems, a gradual reduction of prior dosage is advised. Remove old system before applying new one. Previous antihypertensive medication may have to be continued, particularly with severe hypertension.

Epidural injection

·        Pain management: 30 mcg/hr by continuous epidural infusion.

PEDIATRIC PATIENTS

Safety and efficacy not established.

Pharmacokinetics

Route	Onset	Peak	Duration
Oral	30–60 min	3–5 hr	24 hr
Transdermal	Slow	2–3 days	7 days
Epidural	Rapid	19 min	Variable

Metabolism: Hepatic; T_1/2: 12–16 hr, 19 hr (transdermal system); 48 hr (epidural)

Distribution: Crosses placenta; enters breast milk

Excretion: Urine

Adverse effects

Oral therapy

·        CNS: Drowsiness, sedation, dizziness, headache, fatigue that tend to diminish within 4–6 wk, dreams, nightmares, insomnia, hallucinations, delirium, nervousness, restlessness, anxiety, depression, retinal degeneration

·        CV: CHF, orthostatic hypotension, palpitations, tachycardia, bradycardia, Raynaud's phenomenon, ECG abnormalities manifested as Wenckebach period or ventricular trigeminy

·        Dermatologic: Rash, angioneurotic edema, hives, urticaria, hair thinning and alopecia, pruritus, dryness, itching or burning of the eyes, pallor

·        GI: Dry mouth, constipation, anorexia, malaise, nausea, vomiting, parotid pain, parotitis, mild transient abnormalities in LFTs

·        GU: Impotence, decreased sexual activity, diminished libido, nocturia, difficulty in micturition, urinary retention

·        Other: Weight gain, transient elevation of blood glucose or serum creatine phosphokinase, gynecomastia, weakness, muscle or joint pain, cramps of the lower limbs, dryness of the nasal mucosa, fever

Transdermal system

·        CNS: Drowsiness, fatigue, headache, lethargy, sedation, insomnia, nervousness

·        GI: Dry mouth, constipation, nausea, change in taste, dry throat

·        GU: Impotence, sexual dysfunction

·        Local: Transient localized skin reactions, pruritus, erythema, allergic contact sensitization and contact dermatitis, localized vesiculation, hyperpigmentation, edema, excoriation, burning, papules, throbbing, blanching, generalized macular rash

Interactions

Drug-drug

·        Decreased antihypertensive effects with TCAs (imipramine)

·        Paradoxical hypertension with propranolol; also greater withdrawal hypertension when abruptly discontinued and patient is taking beta-adrenergic blocking agents

Nursing considerations

CLINICAL ALERT!

Name confusion has been reported between clonidine and Klonopin (clonazepam); use caution.

Assessment

·        History: Hypersensitivity to clonidine or adhesive layer components of the transdermal system; severe coronary insufficiency, recent MI, cerebrovascular disease; chronic renal failure; lactation, pregnancy

·        Physical: Body weight; T; skin color, lesions, T; mucous membranes—color, lesion; breast examination; orientation, affect, reflexes; ophthalmologic examination; P, BP, orthostatic BP, perfusion, edema, auscultation; bowel sounds, normal output, liver evaluation, palpation of salivary glands; normal urinary output, voiding pattern; LFTs, ECG

Interventions

·        WARNING: Do not discontinue abruptly; discontinue therapy by reducing the dosage gradually over 2–4 days to avoid rebound hypertension, tachycardia, flushing, nausea, vomiting, cardiac arrhythmias (hypertensive encephalopathy and death have occurred after abrupt cessation of clonidine).

·        Do not discontinue transdermal therapy prior to surgery; monitor BP carefully during surgery; have other BP-controlling drugs readily available.

·        Continue oral clonidine therapy within 4 hr of surgery, then resume as soon as possible thereafter.

·        Store epidural injection at room temperature; discard any unused portions.

·        Reevaluate therapy if clonidine tolerance occurs; giving concomitant diuretic increases the antihypertensive efficacy of clonidine.

·        Monitor BP carefully when discontinuing clonidine; hypertension usually returns within 48 hr.

·        WARNING: Remove transdermal patch before defibrillation to prevent arcing.

·        Assess compliance with drug regimen in a supportive manner with pill counts, or other methods.

Teaching points

·        Take this drug exactly as prescribed. Do not miss doses. Do not discontinue the drug unless instructed by your health care provider. Do not discontinue abruptly; life-threatening adverse effects may occur. If you travel, take an adequate supply of drug.

·        Use the transdermal system as prescribed; refer to directions in package insert, or contact your health care provider with questions. Be sure to remove old systems before applying new ones.

·        Attempt lifestyle changes that will reduce your blood pressure: Stop smoking and using alcohol; lose weight; restrict intake of salt; exercise regularly.

·        Use caution with alcohol. Your sensitivity may increase while using this drug.

·        You may experience these side effects: Drowsiness, dizziness, light-headedness, headache, weakness (often transient; observe caution driving or performing other tasks that require alertness or physical dexterity); dry mouth (sucking on sugarless lozenges or ice chips may help); GI upset (eat frequent small meals); dreams, nightmares (reversible); dizziness, light-headedness when you change position (get up slowly; use caution climbing stairs); impotence, other sexual dysfunction, decreased libido (discuss with care providers); breast enlargement, sore breasts; palpitations.

·        Report urinary retention, changes in vision, blanching of fingers, rash.

Adverse effects in Italic are most common; those in Bold are life-threatening.