Pronunciation: (GWAHN-uh-benz ASS-uh-TATE)Class: Antiadrenergic, centrally acting
Trade Names:Wytensin- Tablets 4 mg- Tablets 8 mg
Appears to stimulate central alpha 2 -adrenergic receptors, inhibiting sympathetic outflow from brain to peripheral circulation.
Bioavailability is about 75%.
Less than 1% is excreted in the urine unchanged.
2 to 4 h.
6 to 8 h.
Indications and Usage
Treatment of hypertension alone or with a thiazide diuretic.
Dosage and AdministrationAdults
PO 4 mg twice daily initially; may increase by 4 to 8 mg daily every 1 to 2 wk; max dose 32 mg twice daily.
Store in tightly closed container in cool environment.
Drug InteractionsCNS depressants
Laboratory Test Interactions
None well documented.
Chest pain; edema; arrhythmias; palpitations; atrioventricular dysfunction.
Drowsiness; sedation; dizziness; anxiety; ataxia; depression; sleep disturbances.
Blurred vision; nasal congestion.
Dry mouth; constipation; diarrhea; nausea; vomiting; abdominal discomfort.
Urinary frequency; disturbances of sexual function.
Increased liver enzymes.
Gynecomastia; muscle or joint pain; weakness; taste disorders.
Monitor BP carefully in patients with coexisting hypertension and chronic hepatic dysfunction or renal impairment.
Category C .
Safety and efficacy in children younger than 12 yr not established.
Special Risk Patients
Use with caution in patients with severe coronary insufficiency, recent MI, or cerebrovascular disease.
Occurs in large percentage of patients.
Do not discontinue therapy without consulting health care provider; drug must be withdrawn gradually to avoid rapid rise in BP.
Marked hypotension, somnolence, lethargy, irritability, miosis, bradycardia.
- Instruct patient and family member in proper technique for taking BP. Advise patient to check and record BP weekly.
- Advise 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 not to discontinue drug abruptly.
- Counsel patient about benefits of weight reduction, exercise, reduction of alcohol and sodium, cessation of smoking.
- Instruct patient to report these symptoms to health care provider: headache, dizziness, weakness, blurred vision.
- 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 prevent 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.
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