Yes

Alpha₂ Agonist

Management of hypertension

C

Hypersensitivity to guanabenz or any component

Use with caution in severe hepatic or renal failure. Avoid in pregnancy and breast-feeding. Safety and efficacy for use in children <12 years of age have not been demonstrated. Use with caution in patients with severe coronary insufficiency, recent MI or cerebrovascular disease. Abrupt discontinuation can result in rebound hypertension. Avoid use in CNS disease, elderly or with other CNS depressants (can cause sedation and drowsiness alone). May cause significant orthostasis.

Higher rates with larger doses

Central nervous system: Drowsiness or sedation, dizziness (12% to 17%), headache (5%)

Cardiovascular: Orthostasis

Gastrointestinal: Xerostomia (28% to 38%)

Neuromuscular & skeletal: Weakness (~10%)

<3%:

Cardiovascular: Arrhythmias, palpitations, chest pain, edema

Central nervous system: Anxiety, ataxia, depression, sleep disturbances

Dermatologic: Rash, pruritus

Endocrine & metabolic: Disturbances of sexual function, gynecomastia, decreased sexual function

Gastrointestinal: Diarrhea, vomiting, constipation, nausea

Genitourinary: Polyuria

Neuromuscular & skeletal: Myalgia

Ocular: Blurring of vision

Respiratory: Nasal congestion, dyspnea

Miscellaneous: Taste disorders

TCAs decrease the hypotensive effect of guanabenz.

Hypoglycemic symptoms may be reduced. Educate patient about decreased signs and symptoms of hypoglycemia or avoid use in patients with frequent episodes of hypoglycemia.

Nitroprusside and guanabenz have additive hypotensive effects.

Noncardioselective beta-blockers (nadolol, propranolol, timolol) may exacerbate rebound hypertension when guanabenz is withdrawn. The beta-blocker should be withdrawn first. The gradual withdrawal of guanabenz or a cardioselective beta-blocker could be substituted.

Protect from light

Stimulates alpha₂-adrenoreceptors in the brain stem, thus activating an inhibitory neuron, resulting in reduced sympathetic outflow, producing a decrease in vasomotor tone and heart rate

Onset of antihypertensive effect: Within 1 hour

Absorption: ~75%

Serum half-life: 7-10 hours

Adults: Oral: Initial: 4 mg twice daily; increase in increments of 4-8 mg/day every 1-2 weeks to a maximum of 32 mg twice daily.

Not routinely used in clinical practice because of significant and marked orthostatic hypotension.

Drowsiness and dizziness are common; may cause anxiety or depression

Has been used to treat ADHD; concurrent use with psychotropics may produce additive sedation and dry mouth; TCAs may decrease the hypotensive effect of guanabenz

No information available to require special precautions

>10% of patients will experience significant dry mouth; normal salivation occurs with cessation of drug therapy

May impair alertness, judgment, coordination; do not abruptly discontinue; do not discontinue without notifying physician

Do not abruptly discontinue

Monitor blood pressure, standing and sitting/supine

Tablet, as acetate: 4 mg, 8 mg

Hall AH, Smolinske SC, Kulig KW, et al, "Guanabenz Overdose," Ann Intern Med, 1985, 102(6):787-8.

Perrone J, Hoffman RS, Jones B, et al, "Guanabenz Induced Hypothermia in a Poisoned Elderly Female," J Toxicol Clin Toxicol, 1994, 32(4):445-9.

Rogers SJ, "Guanabenz Overdose," Ann Intern Med, 1986, 104(3):445.