Home Drug Guide Guanfacine Hydrochloride

Drug Guide

Generic Name

Guanfacine Hydrochloride

Brand Names Tenex, Intuniv

Classification

Therapeutic: Antihypertensive; Attention Deficit Hyperactivity Disorder (ADHD) agent

Pharmacological: Alpha-2 adrenergic agonist

FDA Approved Indications

  • Treatment of hypertension (Tenex)
  • Management of ADHD (Intuniv)

Mechanism of Action

Guanfacine selectively stimulates alpha-2 adrenergic receptors in the central nervous system, reducing sympathetic nerve impulses, which results in decreased blood pressure and modulation of attention and behavior in ADHD.

Dosage and Administration

Adult: For hypertension: Starting dose 0.5 mg once daily, may be titrated up to 2 mg/day. For ADHD: Starting with 1 mg daily, titrate as needed up to 4 mg/day.

Pediatric: ADHD: 1 mg daily, adjustable based on response. Hypertension use is off-label.

Geriatric: Start at lower doses due to increased sensitivity and risk of side effects.

Renal Impairment: Adjust dosage based on severity; consult specific guidelines.

Hepatic Impairment: Use caution; no specific dose adjustment recommended, but monitor closely.

Pharmacokinetics

Absorption: Well absorbed orally.

Distribution: Extensively bound to plasma proteins.

Metabolism: Hepatic metabolism via conjugation and oxidation.

Excretion: Primarily in urine, with some fecal excretion.

Half Life: Approximately 17 hours, allowing for once-daily dosing.

Contraindications

  • Known hypersensitivity to guanfacine or components.

Precautions

  • Use with caution in patients with liver or kidney impairment.
  • Monitor blood pressure closely, especially when initiating or adjusting doses.
  • Avoid abrupt discontinuation to prevent rebound hypertension.
  • Use cautiously in patients with cardiac conduction abnormalities.

Adverse Reactions - Common

  • Sedation (Common)
  • Dry mouth (Common)
  • Fatigue (Common)
  • Dizziness (Common)

Adverse Reactions - Serious

  • Bradycardia (Less common)
  • Hypotension (Less common)
  • Rebound hypertension upon abrupt discontinuation (Rare)

Drug-Drug Interactions

  • CNS depressants (additive sedation)
  • Other antihypertensives (potentiation)
  • MAO inhibitors (risk of hypertensive crisis)

Drug-Food Interactions

  • No significant interactions reported

Drug-Herb Interactions

  • Caution with sedative herbs (e.g., valerian, kava)

Nursing Implications

Assessment: Monitor blood pressure and heart rate regularly. Assess for side effects such as sedation or hypotension.

Diagnoses:

  • Risk for falls related to orthostatic hypotension or sedation.
  • Impaired skin integrity related to dry mouth and sedation.

Implementation: Administer doses as prescribed, preferably at bedtime to minimize sedation effects. Educate patients about rising slowly from sitting or lying positions.

Evaluation: Assess blood pressure and heart rate for effectiveness and adverse effects. Evaluate patient adherence and response.

Patient/Family Teaching

  • Take medication exactly as prescribed.
  • Do not discontinue abruptly to avoid rebound hypertension.
  • Notify healthcare provider if experiencing dizziness, fainting, or severe side effects.
  • Limit activities requiring alertness until response is known.

Special Considerations

Black Box Warnings:

  • Rebound hypertension can occur if medication is stopped abruptly.

Genetic Factors: No specific genetic considerations noted.

Lab Test Interference: May affect blood pressure readings; no interference with lab tests reported.

Overdose Management

Signs/Symptoms: Severe hypotension, bradycardia, drowsiness, lethargy.

Treatment: Supportive care, monitor vital signs, activated charcoal if ingestion recent, and vasopressors for significant hypotension. Gastric lavage may be considered in severe cases.

Storage and Handling

Storage: Store at room temperature, 20°C to 25°C (68°F to 77°F). keep away from moisture and light.

Stability: Stable under recommended storage conditions for at least 2 years.

🛡️ 5 Critical Medication Safety Tips for Nurses

1

Triple-Check High-Risk Medications

Always have another nurse verify insulin, heparin, warfarin, and chemotherapy drugs. These "high-alert" medications cause the most serious errors. Check concentration, dose calculation, and pump settings twice.

2

Know Look-Alike, Sound-Alike Drugs

Common mix-ups: hydromorphone/morphine, Celebrex/Celexa, Zyprexa/Zyrtec. Always use BOTH generic and brand names, read labels twice, and use barcode scanning when available. One wrong letter can be fatal.

3

Assess Before AND After Giving Meds

Check vitals before cardiac meds, pain levels before analgesics, and blood glucose before insulin. Always reassess within 30 minutes to evaluate effectiveness and watch for adverse reactions.

4

Watch for Drug Interactions

Common dangerous combinations: warfarin + aspirin (bleeding), ACE inhibitors + potassium (hyperkalemia), digoxin + diuretics (toxicity). Always check drug interactions before administering new medications.

5

Educate Your Patients

Teach patients medication names, purposes, major side effects, and what to report. Informed patients catch errors and improve compliance. Always encourage questions - an educated patient is a safer patient.

⚡ Remember: When in doubt, don't give it out! It's always safer to double-check than regret later.

⚠️ Medical Disclaimer

This drug guide is for educational purposes only and is NOT intended for clinical use. Always consult current prescribing information, healthcare providers, and institutional protocols before administering any medication. Do not use this information for patient care decisions.