Guanfacine Use and Dosage for ADHD and Hypertension
For ADHD, guanfacine extended-release (Intuniv) is FDA-approved for children and adolescents aged 6-17 years with a recommended starting dose of 1 mg once daily, with weekly titration up to a maximum of 7 mg daily based on response and tolerability. 1
Guanfacine for ADHD
Dosage and Administration
- Starting dose: 1 mg once daily 1
- Titration: Increase by 1 mg per week based on response and tolerability 1
- Maximum recommended dose: 7 mg per day 1
- Typical target dosing range: 0.05 to 0.12 mg/kg/day 1
- Administration timing: Typically given at bedtime to minimize daytime somnolence 2
Efficacy
- Guanfacine is effective for ADHD with effect sizes ranging from 0.43 to 0.62 3
- In clinical trials, guanfacine showed significantly higher efficacy compared to placebo (58.5% vs 29.4% in trials <10 weeks; 63.6% vs 39.7% in trials >10 weeks) 4
Special Considerations for ADHD
- Preferred non-stimulant option for patients with concerns about stimulant abuse or diversion 1
- Better choice for patients with ADHD who are taking venlafaxine due to its selective alpha-2A receptor binding 1
- Not FDA-approved for children under 6 years 1
- Limited data on efficacy and safety in adults; use with caution 1
Guanfacine for Hypertension
Dosage and Administration
- Initial dose: 1 mg daily given at bedtime 2
- If inadequate response after 3-4 weeks: May increase to 2 mg daily 2
- Maximum dose: 3 mg daily (adverse reactions increase significantly above this dose) 2
- Most of the antihypertensive effect is seen at 1 mg 2
Side Effects and Safety Profile
Common Side Effects
- Somnolence (most frequent, affecting up to 38.6% of patients) 4
- Headache (20.5%) 4
- Fatigue (15.2%) 4
- Dry mouth (up to 54% at higher doses) 1
- Dizziness 1, 2
Cardiovascular Effects
- Modest decrease in blood pressure and heart rate (generally not clinically significant in healthy children) 1
- Regular monitoring of blood pressure and heart rate is recommended, especially during dose initiation 1
Important Safety Considerations
- Avoid abrupt discontinuation due to risk of rebound hypertension 1, 2
- When discontinuing, taper gradually (studies show abrupt cessation may be safe in some populations, but tapering is still recommended) 5
- Higher doses (2-3 mg) are associated with significantly more adverse effects than lower doses (0.5-1 mg) 1
- Dropout rates due to adverse effects range from 2% at 0.5 mg to 32% at 3 mg dosing 1
Comparison to Clonidine (Another Alpha-2 Agonist)
- Guanfacine has higher specificity for alpha-2A receptors 1
- Guanfacine has less pronounced sedative effects than clonidine 1
- Guanfacine can be administered once daily, while clonidine typically requires twice-daily dosing 1
- Guanfacine is less potent than clonidine (clonidine is approximately 10 times more potent) 1
Monitoring Recommendations
- Monitor blood pressure and heart rate, especially during initiation 1
- Assess for sedation and alertness 1
- Watch for signs of hypotension or dizziness 1
- Somnolence, sedation, and fatigue typically emerge within the first 2 weeks of dosing and generally resolve by study end 3
Guanfacine offers an effective treatment option for both ADHD and hypertension with a manageable side effect profile when dosed appropriately. The extended-release formulation (Intuniv) is particularly valuable for ADHD treatment in pediatric populations, while immediate-release guanfacine remains an option for hypertension management.