Home Drug Guide Guanabenz Acetate

Drug Guide

Generic Name

Guanabenz Acetate

Brand Names Wytensin

Classification

Therapeutic: Antihypertensive

Pharmacological: Alpha-2 adrenergic agonist

FDA Approved Indications

Hypertension

Mechanism of Action

Guanabenz binds to alpha-2 adrenergic receptors in the central nervous system, reducing sympathetic outflow, thereby decreasing peripheral vascular resistance and lowering blood pressure.

Dosage and Administration

Adult: Initially, 32 mg per day in divided doses; may be titrated up to 64 mg per day based on response.

Pediatric: Not typically used in children.

Geriatric: Start at lower doses due to potential increased sensitivity; titrate carefully.

Renal Impairment: Use with caution; dose adjustments may be necessary based on severity.

Hepatic Impairment: Use with caution; monitor liver function as needed.

Pharmacokinetics

Absorption: Well absorbed orally.

Distribution: Widely distributed; crosses the blood-brain barrier.

Metabolism: Primarily metabolized in the liver.

Excretion: Excreted mainly in the urine.

Half Life: Approximately 8 hours.

Contraindications

Known hypersensitivity to Guanabenz or similar agents.

Precautions

Use with caution in patients with impaired hepatic or renal function.
Careful monitoring of blood pressure is necessary to avoid hypotension.
Potential for sedation and dizziness; caution in activities requiring alertness.

Adverse Reactions - Common

Drowsiness (Common)
Dry mouth (Common)
Dizziness (Common)

Adverse Reactions - Serious

Hypotension (Uncommon)
Rebound hypertension if discontinued abruptly (Uncommon)
Bradycardia (Uncommon)

Drug-Drug Interactions

Additive hypotensive effects with other antihypertensives.
Caution with CNS depressants due to increased sedative effects.

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor blood pressure regularly; assess for signs of hypotension.

Diagnoses:

Ineffective tissue perfusion related to hypotension.
Risk for injury related to dizziness or orthostatic hypotension.

Implementation: Administer as prescribed; advise patient to rise slowly from sitting or lying position.

Evaluation: Evaluate blood pressure control and adverse effects regularly.

Patient/Family Teaching

Take medication exactly as prescribed.
Do not stop abruptly to prevent rebound hypertension.
Rise slowly from sitting or lying to minimize dizziness.
Report symptoms like fainting, excessive dizziness, or symptoms of hypotension.

Special Considerations

Black Box Warnings:

Rebound hypertension if discontinued abruptly.

Genetic Factors: N/A

Lab Test Interference: None significant.

Overdose Management

Signs/Symptoms: Severe hypotension, bradycardia, sedation.

Treatment: Supportive care; monitor cardiovascular status; administer vasopressors if needed; gastric lavage may be considered if ingestion is recent.

Storage and Handling

Storage: Keep at room temperature away from moisture, heat, and light.

Stability: Stable under proper storage conditions.