Guanfacine Liquid Pediatric Dosing for ADHD
For pediatric patients aged 6–17 years with ADHD, start guanfacine liquid (1 mg/mL) at 1 mg (1 mL) once daily in the evening, then increase by 1 mg (1 mL) weekly based on response and tolerability, targeting 0.05–0.12 mg/kg/day with a maximum of 4–7 mg/day. 1, 2
FDA-Approved Age Range and Indications
- Guanfacine is FDA-approved only for children and adolescents aged 6–17 years with ADHD; it is not approved for children younger than 6 years. 1, 2
- For preschool-aged children (4–5 years), behavioral therapy is first-line; guanfacine has not received sufficient rigorous study in this population and should not be used. 1, 2
Starting Dose and Titration Schedule
- Begin with 1 mg (1 mL) once daily, administered in the evening to minimize daytime somnolence. 1, 2
- Increase by 1 mg (1 mL) per week based on clinical response and tolerability. 1, 2
- The typical titration schedule is: Week 1 = 1 mg, Week 2 = 2 mg, Week 3 = 3 mg, Week 4 = 4 mg. 1, 2
Target and Maximum Doses
- Target dose range: 0.05–0.12 mg/kg/day or 1–7 mg/day, adjusted to body weight at approximately 0.1 mg/kg once daily. 1, 2
- Maximum dose: 4 mg/day in most clinical contexts, though doses up to 7 mg/day have been used in clinical trials and may be considered for adolescents with inadequate response. 1, 2, 3
- Weight-adjusted doses >0.08 mg/kg but ≤0.12 mg/kg may provide additional clinical benefits if tolerated, particularly in adolescents. 3
Weight-Based Dosing Examples
| Body Weight | Starting Dose | Target Dose Range (0.05–0.12 mg/kg/day) | Practical Daily Dose |
|---|---|---|---|
| 20 kg | 1 mg (1 mL) | 1–2.4 mg | 1–2 mg |
| 30 kg | 1 mg (1 mL) | 1.5–3.6 mg | 2–3 mg |
| 40 kg | 1 mg (1 mL) | 2–4.8 mg | 2–4 mg |
| 50 kg | 1 mg (1 mL) | 2.5–6 mg | 3–4 mg |
| 60 kg | 1 mg (1 mL) | 3–7.2 mg | 3–4 mg |
| ≥70 kg | 1 mg (1 mL) | 3.5–8.4 mg | 4–7 mg (max) |
Timing of Administration
- Evening administration is strongly preferred because somnolence and fatigue are the most common adverse effects (occurring in 30–39% of patients), and evening dosing minimizes daytime sedation that could interfere with school performance. 1, 2, 4, 5
- Guanfacine extended-release provides "around-the-clock" symptom control lasting approximately 24 hours with once-daily dosing. 1, 2
Expected Onset of Therapeutic Effect
- Therapeutic effects require 2–4 weeks before clinical benefits become apparent, unlike stimulants which work immediately. 1, 2
- Counsel families that patience and consistent daily dosing for several weeks are required before determining treatment response. 1
Baseline and Ongoing Monitoring Parameters
Before Initiating Treatment
- Obtain baseline blood pressure and heart rate before starting guanfacine. 1, 2
- Screen for personal and family cardiac history, including Wolf-Parkinson-White syndrome, unexplained fainting, sudden cardiac death, hypertrophic cardiomyopathy, and long QT syndrome. 1
- Consider ECG if cardiac risk factors are present. 2
During Dose Adjustments and Maintenance
- Monitor blood pressure and heart rate at each dose adjustment and periodically during maintenance therapy. 1, 2
- Expect modest decreases in blood pressure (1–4 mmHg systolic and diastolic) and heart rate (1–2 bpm). 1, 3
- Monitor for hypotension, bradycardia, and excessive somnolence, especially during titration. 1, 3
- Systematically assess ADHD symptoms at each visit using parent and teacher reports. 1
Common Adverse Effects
- Somnolence/sedation (30–39%) is the most frequent adverse effect, typically mild-to-moderate and transient. 1, 4, 5
- Headache (20.5–26%) and fatigue (14–15%) are also common. 1, 4, 5
- Other adverse effects include dry mouth, dizziness, irritability, abdominal pain, and constipation (5–16%). 1, 2
- Cardiovascular-related adverse events are uncommon, though small reductions in blood pressure and pulse rate are expected. 4, 3
Critical Safety Warnings and Discontinuation
- Never abruptly stop guanfacine—it must be tapered by 1 mg every 3–7 days to avoid rebound hypertension. 1, 2
- If the medication needs to be discontinued, taper gradually: reduce by 1 mg (1 mL) every 3–7 days. 1
- Warnings exist regarding hypotension/bradycardia, somnolence/sedation, discontinuation effects, allergic reactions, and cardiac conduction abnormalities. 1
Position in Treatment Algorithm
- Guanfacine is generally recommended as second-line treatment after stimulants due to smaller effect sizes (approximately 0.7 for guanfacine vs. 1.0 for stimulants). 1, 2
- Consider guanfacine as first-line when ADHD co-occurs with:
- Sleep disturbances or insomnia (evening dosing addresses both ADHD and sleep problems). 1
- Tic disorders or Tourette syndrome (guanfacine treats both conditions without worsening tics). 1
- Substance use risk (guanfacine is a non-controlled medication). 1
- Disruptive behavior disorders or oppositional symptoms. 1
Adjunctive Therapy with Stimulants
- Guanfacine extended-release is FDA-approved for adjunctive use with stimulants when stimulant monotherapy provides inadequate symptom control. 1
- Combination therapy allows for lower stimulant doses while maintaining efficacy and potentially reducing stimulant-related adverse effects (e.g., insomnia, rebound symptoms). 1
- When combining guanfacine with stimulants, monitor for opposing cardiovascular effects: stimulants increase heart rate and blood pressure, while guanfacine decreases both. 1
Practical Pitfalls to Avoid
- Do not expect immediate results—counsel families that 2–4 weeks are required for therapeutic effects. 1, 2
- Do not administer in the morning—this wastes the sedative benefit and may cause daytime sleepiness. 1
- Do not use intermittently—consistent daily dosing is required to achieve steady-state therapeutic levels. 1
- Do not overlook multimodal treatment—pharmacotherapy should be combined with behavioral interventions and psychoeducation. 1, 2
- Do not use in children younger than 6 years—behavioral therapy is first-line for ages 4–5 years. 1, 2