Guanfacine

Introduction

• Generic Name: Guanfacine
• Brand Names: Tenex, Intuniv
• Pharmacological Class: Alpha-2 adrenergic agonist
• Mechanism of Action: Guanfacine stimulates alpha-2 adrenergic receptors in the brain which helps decrease heart rate, relax blood vessels, and reduce overall nerve impulses, lowering blood pressure and improving attention and impulse control.

Indications

• Primary Use: Treatment of hypertension (Tenex) and attention deficit hyperactivity disorder (ADHD) in children and adolescents aged 6 to 17 years (Intuniv).
• Other Uses: Off-label uses include treatment for Tourette syndrome, anxiety disorders, and certain withdrawal syndromes.

Dosage

• Adults (Tenex): Typically, 1 mg orally once daily at bedtime for hypertension, adjust dose based on response and tolerability.
• Children (Intuniv for ADHD): Start with 1 mg once daily; titrate according to response up to a maximum of 4 mg once daily.
• Elderly: May require lower doses due to increased sensitivity and risk of side effects.

Administration

• Method: Oral intake.
• Precautions: Should be taken at the same time each day to maintain even levels of medication in the blood. Do not take with high-fat meals as it can increase the absorption of the extended-release form (Intuniv) too quickly.

Forms Available

• Immediate-Release Tablets (Tenex): 1 mg, 2 mg
• Extended-Release Tablets (Intuniv): 1 mg, 2 mg, 3 mg, 4 mg

Side Effects

• Common: Drowsiness, headache, fatigue, abdominal pain, and dizziness.
• Less Common: Dry mouth, constipation, decreased blood pressure, irritability.
• Rare but Serious: Slow heart rate, severe hypotension, syncope.

Warnings

• Black Box Warning: None.
• Contraindications: Hypersensitivity to guanfacine, history of syncope, severe correlated cardiac conditions like bradycardia or heart block.

Precautions

• General: Withdrawal of the drug should be done gradually to avoid potential severe rebound hypertension.
• Health Conditions: Monitor patients for signs of heart issues, depression, or suicidal thoughts, particularly in patients with a history of these conditions.

Interactions

• Medications: Increased risk of side effects with other central nervous system depressants and blood pressure medications.
• Food: High-fat meals can increase the absorption rate of extended-release guanfacine, potentially leading to side effects.

Monitoring Parameters

• Blood Pressure and Heart Rate: Regular monitoring, especially when initiating therapy or adjusting dose.
• Mental Health: Assessment for new or worsening symptoms of depression or suicidal thoughts.

Use in Children

• Guidelines: Approved for the treatment of ADHD in children aged 6 to 17 years. Should be used under the supervision of a healthcare provider.

Use in Pregnancy

• FDA Category: B. Should be used during pregnancy only if clearly needed and the benefits outweigh the risks.

Use in Elderly

• Considerations: Increased likelihood of side effects such as bradycardia and hypotension. Careful monitoring and dose adjustments may be necessary.

Use in Kidney Disease

• Adjustments: May require dose adjustments depending on the severity of renal impairment.

Use in Liver Disease

• Caution: Use with caution; liver impairment could alter drug metabolism and excretion.

Patient Counselling Points

• Medication Use: Importance of adherence to prescribed dosages; do not discontinue abruptly.
• Side Effects: Be aware of signs of low blood pressure such as dizziness and educate on how to manage them.
• Lifestyle: Advise avoiding alcohol and other CNS depressants that could exacerbate side effects.

Table of Brand Names, Manufacturer, and Prices in USD

15 FAQs with Answers

1. What is Guanfacine used for? – It’s used to treat high blood pressure and ADHD.
2. How does Guanfacine work? – It works by activating alpha-2 adrenergic receptors which help to reduce nerve impulses that tighten blood vessels and cause inattention and hyperactivity.
3. Can Guanfacine be used in adults for ADHD? – It’s primarily approved for children but may be used off-label in adults.
4. What are the potential side effects of Guanfacine? – Includes dizziness, fatigue, and low blood pressure.
5. How should Guanfacine be taken? – As directed by your healthcare provider, typically at the same time each day.
6. Can Guanfacine cause withdrawal symptoms? – Yes, abrupt discontinuation can lead to rebound hypertension.
7. Is Guanfacine safe during pregnancy? – Classified as Category B; discuss potential risks and benefits with your doctor.
8. Can I drink alcohol while taking Guanfacine? – Alcohol should be avoided as it can increase the risk of side effects.
9. What should I do if I miss a dose? – Take it as soon as you remember unless it’s close to your next dose. Do not double up doses.
10. How does Guanfacine affect blood pressure? – It can significantly lower blood pressure.
11. Is Guanfacine addictive? – No, but it should be used as prescribed to avoid potential health risks.
12. How long does it take for Guanfacine to work? – It may take several weeks to see the full effect on ADHD symptoms.
13. Can Guanfacine be stopped suddenly? – No, it should be tapered off under medical supervision to prevent rebound effects.
14. What other treatments should be used with Guanfacine for ADHD? – Often used in conjunction with behavioral therapy and educational interventions.
15. Who should not take Guanfacine? – Individuals with certain heart conditions, severe liver disease, or sensitivity to the drug.