Can I add extended‑release mixed amphetamine salts (Adderall XR) in the morning for my 6‑year‑old, 20‑kg child who is stable on immediate‑release guanfacine 3 mg daily divided TID and risperidone 0.5 mg at bedtime?

Adding Adderall XR to Current Medication Regimen

Yes, you can add Adderall XR in the morning to this child's current regimen of guanfacine and risperidone, as stimulants and alpha-2 agonists like guanfacine are commonly combined with demonstrated safety and efficacy for ADHD symptom control. 1

Rationale for Combination Therapy

• Guanfacine and stimulants are frequently co-administered when monotherapy with either agent provides suboptimal ADHD symptom control, with studies showing this combination is generally safe and produces clinically meaningful symptom improvement 1
• The child's current guanfacine regimen (3 mg daily divided TID) represents a non-stimulant approach that may benefit from augmentation with a stimulant for more robust symptom control 2
• Stimulants remain first-line treatment for ADHD with larger effect sizes than non-stimulants like guanfacine, which are generally considered second-line agents 2

Dosing Strategy for This 20-kg Child

Start with Adderall XR 5 mg once daily in the morning 2

• For children weighing less than 25 kg (55 lbs), the American Academy of Child and Adolescent Psychiatry recommends starting with 2.5 mg of mixed amphetamine salts, but since Adderall XR comes in 5 mg as the lowest dose, this is the appropriate starting point 2
• Do not use the 15 mg dose listed in the titration table for children under 20 kg (45 lbs) – this dose should be omitted in small children 2
• Adderall XR provides once-daily dosing with effects lasting throughout the school day, eliminating the need for midday administration 3

Titration Schedule

• Week 1: Start 5 mg Adderall XR in the morning 2
• Week 2: If inadequate response and no prohibitive side effects, increase to 10 mg 2
• Week 3-4: Continue monitoring; further increases should be guided by symptom response and tolerability 2
• Obtain ADHD rating scales from parents and teachers before each dose adjustment 2

Safety Monitoring Requirements

At each visit, assess the following 2:

• Blood pressure and pulse (stimulants can cause modest increases; guanfacine may cause modest decreases, potentially offsetting each other) 2, 1
• Height and weight (stimulants suppress appetite more than guanfacine) 2
• Side effects using standardized rating scales 2
• Sleep quality and duration 2

Expected Side Effects with Combination Therapy

The most common treatment-related adverse events when combining guanfacine with stimulants include 1:

• Upper abdominal pain (25.3%)
• Fatigue (24.0%)
• Irritability (22.7%)
• Headache (20.0%)
• Somnolence (18.7%)

Most adverse events are mild to moderate in severity 1

Advantages of This Combination

• Guanfacine provides "around-the-clock" symptom coverage without the wearing-off pattern of stimulants, potentially smoothing out the day-long response 2
• Guanfacine may help mitigate stimulant-induced sleep disturbances and cardiovascular effects (elevated blood pressure and heart rate) 2
• The combination addresses both core ADHD symptoms and may improve oppositional behaviors 4
• Nearly 90% of children respond when both stimulant classes are tried, compared to 70% with a single stimulant 2

Critical Pitfalls to Avoid

• Do not exceed age- and weight-appropriate maximum doses: For this 20-kg child, total daily amphetamine doses should remain conservative during titration 2
• Do not abruptly discontinue guanfacine if you decide to transition to stimulant monotherapy – alpha-2 agonists require gradual tapering to avoid rebound hypertension 5
• Do not assume the risperidone 0.5 mg at bedtime is contraindicated with this combination, but monitor carefully for excessive sedation given the additive CNS depressant effects of guanfacine and risperidone 1
• Do not skip cardiovascular monitoring: While investigator-rated adverse events due to blood pressure or heart rate changes are infrequent with this combination, baseline and ongoing monitoring is essential 1

Timing Considerations

• Administer Adderall XR in the morning after breakfast to minimize gastrointestinal side effects and ensure coverage throughout the school day 3
• Continue the current guanfacine TID schedule (morning, midday, evening) to maintain steady-state levels 5
• Maintain risperidone at bedtime 1

When to Reassess the Regimen

• If after 4-6 weeks of optimized Adderall XR dosing the child shows inadequate response, consider switching to methylphenidate-based stimulants rather than increasing amphetamine doses further 2
• If prohibitive side effects occur (severe anorexia, severe insomnia >1.5 hours, marked tics, severe headaches, severe anxiety, or aggression), reduce or discontinue the stimulant 2