Clonidine hydrochloride
Clonidine hydrochloride (Catapres)
Clonidine hydrochloride
( KLOH-nih-deen)
Pregnancy Category: C Apo-Clonidine ; Catapres; Catapres-TTS-1, -2, and -3; Dixarit ; Duraclon Novo-Clonidine Nu-Clonidine (Rx)

Classification: Antihypertensive, centrally acting antiadrenergic

See Also: See also Antihypertensive Agents .

Action/Kinetics: Stimulates alpha-adrenergic receptors of the CNS, which results in inhibition of the sympathetic vasomotor centers and decreased nerve impulses. Thus, bradycardia and a fall in both SBP and DBP occur. Plasma renin levels are decreased, while peripheral venous pressure remains unchanged. Few orthostatic effects. Although NaCl excretion is markedly decreased, potassium excretion remains unchanged. To relieve spasticity, it decreases excitatory amino acids by central presynaptic þ-receptor agonism. Tolerance to the drug may develop. Onset, PO: 30-60 min; transdermal: 2-3 days. Peak plasma levels, PO: 3-5 hr; transdermal: 2-3 days. Maximum effect, PO: 2-4 hr. Duration, PO: 12-24 hr; transdermal: 7 days (with system in place). t 1/2: 12-16 hr. Approximately 50% excreted unchanged in the urine; 20% excreted through the feces.
The transdermal dosage form contains the following levels of drug: Catapres-TTS-1 contains 2.5 mg clonidine (surface area 3.5 cm ²), with 0.1 mg released daily; Catapres-TTS-2 contains 5 mg clonidine (surface area 7 cm ²), with 0.2 mg released daily; and Catapres-TTS-3 contains 7.5 mg clonidine (surface area 10.5 cm ²), with 0.3 mg released daily.

Uses: Oral, Transdermal: Mild to moderate hypertension. A diuretic or other antihypertensive drugs, or both, are often used concomitantly. Treat spasticity. Investigational: Alcohol withdrawal, atrial fibrillation, attention deficit hyperactivity disorder, constitutional growth delay in children, cyclosporine-associated nephrotoxicity, diabetic diarrhea, Gilles de la Tourette's syndrome, hyperhidrosis, hypertensive emergencies, mania, menopausal flushing, opiate detoxification, diagnosis of pheochromocytoma, postherpetic neuralgia, psychosis in schizophrenia, reduce allergen-induced inflammatory reactions in extrinsic asthma, restless leg syndrome, facilitate smoking cessation, ulcerative colitis.
Epidural: With opiates for severe pain in cancer clients not relieved by opiate analgesics alone. Most effective for neuropathic pain.

Contraindications: Epidurally: Presence of an injection site infection, clients on anticoagulant therapy, in bleeding diathesis, administration above the C4 dermatome. For obstetric, postpartum, or perioperative pain.

Special Concerns: Use with caution during lactation and in the presence of severe coronary insufficiency, recent MI, cerebrovascular disease, or chronic renal failure. Safe use in children not established; when used for attention deficit disorder, even one extra dose can be harmful. Geriatric clients may be more sensitive to the hypotensive effects; a decreased dosage may also be necessary in these clients due to age-related decreases in renal function. For children, restrict epidural use to severe intractable pain from malignancy that is not responsive to epidural or spinal opiates or other analgesic approaches.

Side Effects: CNS: Drowsiness (common), sedation, confusion, dizziness, headache, fatigue, malaise, nightmares, nervousness, restlessness, anxiety, mental depression, increased dreaming, insomnia, hallucinations, delirium, agitation. GI: Dry mouth (common), constipation, anorexia, N&V;, parotid pain, weight gain, hepatitis, parotitis, ileus, pseudo-obstruction, abdominal pain. CV: CHF, severe hypotension, Raynaud's phenomenon, abnormalities in ECG, palpitations, tachycardia and bradycardia, postural hypotension, conduction disturbances, sinus bradycardia, CVA. Dermatologic: Urticaria, skin rashes, sweating, angioneurotic edema pruritus, thinning of hair, alopecia, skin ulcer. GU: Impotence, urinary retention, decreased sexual activity, loss of libido, nocturia, difficulty in urination, UTI. Respiratory: Hypoventilation, dyspnea. Musculoskeletal: Muscle or joint pain, leg cramps, weakness. Other: Gynecomastia, increase in blood glucose (transient), increased sensitivity to alcohol, chest pain, tinnitus, hyperaesthesia, pain, infection, thrombocytopenia, syncope, blurred vision, withdrawal syndrome, dryness of mucous membranes of nose; itching, burning, dryness of eyes; skin pallor, fever.

NOTE: When used for attention deficit hyperactivity disorder in children, can cause serious side effects, including bradycardia, hypotension, and respiratory depression.

Laboratory Test Alterations: Transient blood glucose, serum phosphatase, and serum CPK. Weakly + Coombs' test. Alteration of electrolyte balance.

Overdose Management: Symptoms: Hypotension, bradycardia, respiratory and CNS depression, hypoventilation, hypothermia, apnea, miosis, agitation, irritability, lethargy, seizures, cardiac conduction defects, arrhythmias transient hypertension, diarrhea, vomiting. Treatment: Maintain respiration; perform gastric lavage followed by activated charcoal. Magnesium sulfate may be used to hasten the rate of transport through the GI tract. IV atropine sulfate (0.6 mg for adults; 0.01 mg/kg for children), epinephrine, tolazoline, or dopamine to treat persistent bradycardia. IV fluids and elevation of the legs are used to reverse hypotension; if unresponsive to these measures, dopamine (2-20 mcg/kg/min) or tolazoline (1 mg/kg IV, up to a maximum of 10 mg/dose) may be used. To treat hypertension, diazoxide, IV furosemide, or an alpha-adrenergic blocking drug may be used.

Drug Interactions: Alcohol / Depressant effects Beta-adrenergic blocking agents / Paradoxical hypertension; also, severity of rebound hypertension following clonidine withdrawal CNS depressants / CNS depressant effect Levodopa / Levodopa effect Local anesthetics / Epidural clonidine prolonged duration of epidural local anesthetics Prazosin / Clonidine antihypertensive effect Narcotic analgesics / Potentiation of clonidine hypotensive effect Tolazoline / Blocks antihypertensive effect Tricyclic antidepressants / Blocks antihypertensive effect Verapamil / Risk of AV block and severe hypotension

How Supplied: Film, Extended Release: 0.1 mg/24 hrs, 0.2 mg/24 hrs, 0.3 mg/24 hrs; Injection: 0.1 mg/mL; Tablet: 0.1 mg, 0.2 mg, 0.3 mg

Dosage
?Tablets Hypertension.
Initial: 100 mcg b.i.d.; then, increase by 100-200 mcg/day until desired response is attained; maintenance: 200-600 mcg/day in divided doses (maximum: 2400 mcg/day). Tolerance necessitates increased dosage or concomitant administration of a diuretic. Gradual increase of dosage after initiation minimizes side effects. Pediatric: 50-400 mcg b.i.d.
NOTE: In hypertensive clients unable to take PO medication, clonidine may be administered sublingually at doses of 200-400 mcg/day.
Treat spasticity.
Adults and children: 0.1-0.3 mg/day, given in divided doses.
Alcohol withdrawal.
300-600 mcg q 6 hr.
Atrial fibrillation.
75 mcg 1-2 times/day with or without digoxin.
Attention deficit hyperactivity disorder.
5 mcg/kg/day for 8 weeks.
Constitutional growth delay in children.
37.5-150 mcg/m ²/day.
Diabetic diarrhea.
100-600 mcg q 12 hr.
Gilles de la Tourette syndrome.
150-200 mcg/day.
Hyperhidrosis.
250 mcg 3-5 times/day.
Hypertensive urgency (diastolic > 120 mm Hg).
Initial: 100-200 mcg; then, 50- 100 mcg q hr to a maximum of 800 mcg.
Menopausal flushing.
100-400 mcg/day.
Withdrawal from opiate dependence.
15-16 mcg/kg/day.
Diagnosis of pheochromocytoma.
300 mcg.
Postherpetic neuralgia.
200 mcg/day.
Psychosis in schizophrenia.
Less than 900 mcg/day.
Reduce allergen-induced inflammation in extrinsic asthma.
150 mcg for 3 days or 75 mcg/1.5 mL saline by inhalation.
Restless leg syndrome.
100-300 mcg/day, up to 900 mcg/day.
Facilitate cessation of smoking.
150-400 mcg/day.
Ulcerative colitis.
300 mcg t.i.d.
?Transdermal Hypertension.
Initial: Use 0.1-mg system; then, if after 1-2 weeks adequate control has not been achieved, can use another 0.1-mg system or a larger system. The antihypertensive effect may not be seen for 2-3 days. The system should be changed q 7 days.
Treat spasticity.
Adults and children: 0.1-0.3 mg; apply patch q 7 days.
Cyclosporine-associated nephrotoxicity.
100-200 mcg/day.
Diabetic diarrhea.
0.3 mg/24 hr patch (1 or 2 patches/week).
Menopausal flushing.
100 mcg/24-hr patch.
Facilitate cessation of smoking.
200 mcg/24-hr patch.
?Epidural infusion Analgesia.
Initial: 30 mcg/hr. Dose may then be titrated up or down, depending on pain relief and side effects.