Starting Dose of Guanfacine for ADHD
The recommended starting dose of guanfacine for ADHD is 1 mg once daily, taken at bedtime to minimize somnolence. 1, 2
Dosing Guidelines
- Initial dose: 1 mg once daily at bedtime
- Titration: May 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
Age-Specific Considerations
- FDA-approved for children and adolescents aged 6-17 years 1
- Not FDA-approved for preschool children (under 6 years) 1
- Limited data on efficacy and safety in adults; use with caution 1
Administration Pearls
- Taking guanfacine at bedtime helps minimize daytime somnolence, which affects up to 38.6% of patients 3
- Extended-release formulation allows for once-daily dosing, improving adherence compared to immediate-release formulations that require multiple daily doses 4
- Most of the therapeutic effect is seen at the 1 mg dose, though some patients may require higher doses 2
Monitoring and Safety
- Blood pressure and heart rate monitoring are crucial, especially during initiation 1
- Guanfacine can cause modest cardiovascular effects, including mild decreases in blood pressure and heart rate 1
- Common side effects include somnolence (38.6%), headaches (20.5%), and fatigue (15.2%) 3
- Higher doses (2-3 mg) are associated with significantly more adverse effects than lower doses (0.5-1 mg) 1
Important Precautions
- Abrupt discontinuation should be avoided; taper gradually to prevent rebound effects 1, 4
- When rebound occurs, it typically happens after 2-4 days, which is delayed compared to clonidine 2
- In most cases, after abrupt withdrawal, blood pressure returns to pretreatment levels slowly (within 2-4 days) without ill effects 2
Clinical Advantages
- As a non-stimulant medication, guanfacine has less abuse potential than stimulants, making it suitable for adolescents with substance abuse concerns 1
- Guanfacine is a preferred choice for patients with ADHD who are taking venlafaxine, due to its selective alpha-2A receptor binding and better side effect profile when combined with antidepressants 1