Intuniv

(guanfacine ER)

Forms/Strengths

• Tablets: 1 mg, 2 mg, 3 mg, 4 mg 

Dosing

• Age: ≥ 6 y/o
• Duration: ~ 24 hours
• Considerations: Avoid high-fat meals; do not crush, chew, or break tablets
• Initial Dose: 1 mg daily 
• Titration: 1 mg/week
• Max Dose:
  • 25 - 33.9 kg: 2 - 3 mg/day
  • 34 - 41.4 kg: 2 - 4 mg/day
  • 41.5 - 49.4 kg: 3 - 5 mg/day
  • 49.5 - 58.4 kg: 3 - 6 mg/day
  • 58.5 - 91 kg: 4 - 7 mg/day
  • 91+ kg: 5 - 7 mg/day

Quick Facts

• Guanfacine (Intuniv) is a selective alpha-2A adrenergic receptor agonist; enhances prefrontal cortex regulation
• Reduces impulsivity and hyperactivity; may be less effective for inattention
• Non-stimulant option for ADHD; useful as adjunct therapy with stimulants
• Primarily metabolized by CYP3A4; dose adjustments may be necessary with CYP3A4 inhibitors or inducers
• Common side effects: drowsiness, fatigue, hypotension, dry mouth
  

Indications

•  ADHD (ICD-10: F90.0)

Off-Label Uses

• Oppositional Defiant Disorder (F91.3): May help manage irritability, anger outbursts, and impulsive aggression.
• Anxiety Disorders (F41.9): Sometimes used to reduce symptoms of anxiety and related somatic complaints.  
• Tic Disorders/Tourette’s Syndrome (F95.2): Occasionally employed off-label to help reduce tics.  
• Autism Spectrum Disorder-Associated Irritability (F84.0): May help in managing irritability and aggression in some cases.

How to Take

• Take once daily, preferably at the same time each day.
• Swallow the tablet whole; do not crush, chew, or split.
• Take with or without food, but be consistent with food intake to maintain stable absorption.
• If a dose is missed, take it as soon as possible unless it is close to the next dose—do not double up.
• Do not abruptly stop taking; tapering may be required to prevent rebound hypertension.
  

Side Effects

• Common: Sedation, somnolence, headache, abdominal pain, hypotension, bradycardia.

  Serious: Syncope, rebound hypertension, cardiac conduction abnormalitie

Monitoring / Labs

• Cardiovascular: Baseline and routine monitoring of heart rate and blood pressure.
• Psychiatric Symptoms: Observe for mood changes, anxiety, or psychosis.

Education

• When to Call the Doctor:

  • Severe dizziness, fainting, or low blood pressure.
  • Slow or irregular heart rate.
  • Excessive drowsiness or difficulty waking.
  • Mood changes, depression, or unusual behavior.
  • Severe headache, blurred vision, or confusion (possible hypertensive rebound if stopped abruptly).

• Safety Tips:

  • Monitor blood pressure and heart rate regularly.
  • Avoid alcohol and sedatives, which may enhance drowsiness.
  • Rise slowly from sitting or lying positions to prevent dizziness.
  • Use caution when driving or operating heavy machinery due to possible sedation.
  • Taper gradually when discontinuing to avoid withdrawal symptoms.

• Parent Tips for Pediatric Patients:

  • May cause daytime drowsiness; consider giving the dose at bedtime if drowsiness is problematic.
  • Monitor for irritability, mood swings, or behavioral changes.
  • Encourage hydration and balanced nutrition to minimize side effects.
  • Ensure children do not engage in high-risk activities (e.g., swimming, biking) if excessively drowsy.

Additional Information

• Contraindications:

  • Hypersensitivity to guanfacine or formulation components.
  • Use with caution in patients with severe heart disease, bradycardia, or hypotension.

• Pregnancy:

  • Category B; no well-controlled studies in pregnant women, but animal studies suggest minimal risk.

• Lactation:

  • Excreted in breast milk; use with caution due to potential effects on infant blood pressure.

• Drug Interactions:

  • CNS depressants (e.g., alcohol, benzodiazepines) may increase sedation.
  • Beta-blockers may enhance bradycardia; caution when using together.
  • Stimulants (e.g., amphetamines) may counteract guanfacine’s effects.
  • Antihypertensive medications may lead to excessive blood pressure lowering.