Guanfacine HCl

A to Z Drug Facts

 Action Appears to stimulate central alpha₂-adrenergic receptors, with decreased sympathetic outflow, causing decrease in peripheral vascular resistance and reduction in heart rate.

 Indications Treatment of hypertension. unlabeled use(s): Amelioration of heroin withdrawal symptoms.

 Contraindications Standard considerations.

 Route/Dosage

ADULTS: PO 1 mg daily at bedtime; may increase gradually up to 3 mg daily.

 Interactions

Alcohol, CNS depressants: Increased CNS depression. Barbiturates, phenytoin: Decreased guanfacine levels with loss of antihypertensive effect.

 Lab Test Interferences None well documented.

 Adverse Reactions

CV: Chest pain; bradycardia; palpitations. CNS: Somnolence; drowsiness; dizziness; headache; sleep disturbances; insomnia; confusion; depression. DERM: Dermatitis; pruritus; sweating. EENT: Conjunctivitis; visual disturbance; tinnitus; rhinitis; taste perversion. GI: Dry mouth; constipation; diarrhea; nausea; abdominal discomfort; dyspnea. GU: Urinary incontinence; testicular disorder; decreased libido; impotence. OTHER: Paresthesia; paresis; leg cramps; hypokinesia.

 Precautions

Pregnancy: Category B. Lactation: Excreted in breast milk. Children: Safety and efficacy in children < 12 yr not established. Special risk patients: Use with caution in patients with severe coronary insufficiency, recent MI, cerebrovascular disease or chronic renal or hepatic impairment. Sedation: Occurs in a large percentage of patients. Withdrawal: Do not discontinue therapy without consulting health care provider; drug must be withdrawn gradually to avoid rapid rise in BP (rebound hypertension).

 Administration/Storage

• Administer medication at bedtime.
• Give with food or milk if patient experiences stomach upset.
• Store in tightly closed container and protect from light.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies. Note cardiovascular, cerebrovascular, renal, or hepatic disease.
• Take patient's BP (lying, sitting, standing) and pulse before administering drug. Monitor periodically throughout therapy.
• Notify health care provider if these signs occur: Hypotension, chest pain, palpitations, anemia, leukopenia, thrombocytopenia, edema, dyspnea, diarrhea.

 Patient/Family Education

• Instruct patient to take medication at bedtime.
• Teach patient proper technique for taking BP. Advise patient to check BP weekly.
• Instruct patient not to discontinue drug abruptly.
• Advise patient on benefits of weight loss, exercise, reduction of alcohol and sodium intake and cessation of smoking.
• Instruct patient to lie down if dizziness or blurred vision occurs.
• Explain that impotence may occur but is reversible. Tell patient to report to health care provider.
• Instruct patient to report these symptoms to health care provider: Dizziness, constipation, headache, insomnia, nausea, sweating, or weakness.
• Advise patient to take sips of water frequently, suck on ice chips or sugarless hard candy, or chew sugarless gum if dry mouth occurs.
• Caution patient to avoid sudden position changes to avoid orthostatic hypotension.
• Instruct patient to avoid intake of alcoholic beverages or other CNS depressants.
• Advise patient that drug may cause drowsiness and to use caution while driving or performing other tasks requiring mental alertness.
• Instruct patient not to take otc medications without consulting health care provider.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts