Guanfacine Dosing for ADHD
The recommended dosing for guanfacine in ADHD treatment is to start at a low dose and titrate gradually, with an effective range of 1-4 mg/day and a typical maximum daily dose of 4 mg/day. 1
Dosing Guidelines
Initial Dosing and Titration
- Start with a low dose to minimize side effects
- Extended-release formulation (GXR) is preferred for better tolerability 2
- Dose should be titrated gradually based on clinical response and tolerability
Dosing by Age Group
- Children and adolescents (6-17 years):
Administration Considerations
- Can be administered in the morning or evening 5
- Evening dosing may be preferable to minimize daytime sedation
- Should be taken consistently with respect to food intake
- Do not substitute immediate-release guanfacine for extended-release on a milligram-for-milligram basis 2
Efficacy and Response
- Guanfacine has demonstrated significant efficacy for ADHD symptoms with effect sizes ranging from 0.43 to 0.62 3
- Response rates (defined as CGI-I score ≤2) range from 58.5% to 63.6% compared to 29.4% to 39.7% with placebo 6
- Efficacy is observed across both shorter (<10 weeks) and longer (>10 weeks) treatment durations 6
- Particularly useful for ADHD with comorbidities such as tic disorders, sleep disturbances, or autism spectrum disorder 1
Monitoring and Safety Considerations
Common Side Effects
- Somnolence (38.6%), headache (20.5%), and fatigue (15.2%) are most common 6
- Sedation-related side effects typically emerge within the first 2 weeks and often resolve with continued treatment 3
- Decreased appetite may occur
Cardiovascular Monitoring
- Monitor blood pressure and heart rate regularly
- Blood pressure typically declines in the first 4 weeks, with return nearly to baseline by 8 weeks 4
- Pulse rate follows a similar pattern but may remain lower than baseline 4
- Cardiovascular history should be obtained, and ECG should be considered if risk factors are present 1
Special Populations
- Guanfacine is more selective for alpha-2A receptors compared to clonidine, resulting in less sedation and more stable blood pressure effects 1
- Has shown efficacy in children with autism spectrum disorder and hyperactivity at similar doses (modal dose 3 mg/day, range 1-4 mg/day) 4
Clinical Pearls
- Guanfacine is considered a second-line or adjunctive therapy when stimulants are not fully effective 1
- Can be used as monotherapy or as an adjunct to stimulants for patients with partial response 5
- Doses above 4 mg/day cannot be recommended due to lack of study data at higher doses 2
- Must be tapered gradually upon discontinuation to prevent rebound effects
- Metabolized primarily by CYP3A4, with predominantly renal excretion 1