Intuniv (Guanfacine Extended-Release) Dosing for ADHD
Start with 1 mg once daily in the morning, then titrate upward by 1 mg per week based on response and tolerability, targeting a dose range of 0.05 to 0.12 mg/kg/day or 1 to 7 mg/day. 1
Starting Dose
- Begin with 1 mg once daily 1
- Administer in the morning as a single daily dose 1
- This applies to children and adolescents aged 6-17 years, the approved population in Canada 1
Titration Schedule
- Increase by 1 mg increments weekly based on clinical response and tolerability 1
- Continue weekly titration until reaching the target therapeutic range or maximum tolerated dose 1
- Monitor for efficacy using standardized ADHD rating scales from parents and teachers during titration 1
Target Dose Range
- Weight-based dosing: 0.05 to 0.12 mg/kg/day 1
- Absolute dose range: 1 to 7 mg/day 1
- The modal dose in clinical trials was typically 3 mg/day, with a range of 1-4 mg/day 2
Important Clinical Considerations
Onset of Action
- Allow 2-4 weeks to observe full therapeutic effects after reaching target dose 1
- This delayed onset differs from stimulants, which show rapid response 1
Monitoring Parameters
- Blood pressure and pulse should be monitored during titration and at steady state 1
- Expect modest reductions in blood pressure and heart rate, which are common but typically not clinically significant 3, 2
- In one study, blood pressure declined in the first 4 weeks but returned nearly to baseline by week 8 2
Common Adverse Effects
- Somnolence/sedation is the most frequent adverse effect and may require evening dosing adjustment 1, 4
- Fatigue, decreased appetite, dry mouth, and hypotension are also common 1
- Headache and irritability may occur during titration 1
Discontinuation
- Do not stop abruptly if used for more than 9 weeks, especially at higher doses 1
- Taper gradually to minimize risk of rebound hypertension and tachycardia 1
- However, research in healthy adults showed abrupt cessation of doses up to 4 mg/day did not cause significant blood pressure elevation 5
Special Populations
Adults
- Limited efficacy data exist for adults with ADHD 1
- Guanfacine is approved in Canada only for children and adolescents aged 6-17 years 1
- Alternative agents are generally preferred for adult ADHD 1
Pregnancy and Breastfeeding
- Use with caution—very limited safety data available 1
- No published studies exist on guanfacine use during breastfeeding 1
- One small study in preeclampsia showed no congenital malformations, but 20% of infants had low birth weight 1
- Alternative agents are preferred in pregnancy and lactation 1
Positioning in Treatment Algorithm
- Guanfacine is a second-line agent for ADHD 1
- Stimulants (methylphenidate, amphetamines) remain first-line therapy due to larger effect sizes 1, 4
- Consider guanfacine as first-line when stimulants are contraindicated or in specific comorbidities including: sleep disorders, substance use disorders, disruptive behavior disorders, or tic/Tourette's disorder 1
- Guanfacine provides "around-the-clock" symptom coverage, unlike short-acting stimulants 1
Key Pitfalls to Avoid
- Do not expect immediate response—allow adequate time (2-4 weeks) at target dose before declaring treatment failure 1
- Do not use weight-adjusted dosing exclusively—the absolute dose range of 1-7 mg/day is more practical than strict mg/kg calculations 1
- Do not combine with CYP3A4 inhibitors or inducers without dose adjustment, as these affect guanfacine metabolism 1
- Monitor for excessive sedation, which may require dose reduction or timing adjustment 1, 4, 3