At what time of day is Guanfacine (Intuniv) typically administered to a patient, especially children and adolescents with Attention Deficit Hyperactivity Disorder (ADHD)?

Timing of Guanfacine Administration

Guanfacine extended-release for ADHD should be administered in the evening to minimize daytime somnolence and fatigue, though morning administration is equally effective if sedation is not problematic. 1

Recommended Administration Time

Evening dosing is generally preferable because somnolence and fatigue are the most common adverse effects of guanfacine, occurring in approximately 15-20% of patients. 1 Evening administration allows these sedative effects to occur during sleep hours rather than interfering with school performance and daily activities. 1

However, both morning and evening administration provide equivalent efficacy throughout the 24-hour period, with once-daily dosing delivering "around-the-clock" symptom control. 1, 2 A controlled study demonstrated that children receiving guanfacine in either the morning or evening showed significant improvements in ADHD symptoms assessed during morning, afternoon, and evening periods compared to placebo (p<0.001 for both timing groups). 2

Clinical Decision Algorithm

Choose evening administration when:

• Sedation or somnolence is a concern 1
• Once-daily dosing convenience is preferred 1
• The patient has cardiovascular risk factors (allows monitoring of BP/HR effects during sleep) 3

Consider morning administration when:

• Evening sedation interferes with homework or family activities
• The patient tolerates the medication well without significant somnolence 2
• Bedtime dosing compliance is problematic

Important Caveats

Therapeutic effects are delayed 2-4 weeks, unlike stimulants which work immediately, so families must understand that timing adjustments for side effects can be made without compromising the eventual therapeutic response. 1

The extended-release formulation provides continuous 24-hour coverage regardless of administration time, which is a major advantage over stimulants that have limited duration and potential rebound symptoms. 1

Contrast with Immediate-Release Formulation

Note that the FDA-approved immediate-release guanfacine for hypertension is dosed at bedtime to minimize somnolence in that indication. 4 However, this should not be confused with the extended-release formulation used for ADHD, which has different pharmacokinetics and can be dosed flexibly. 5