Strattera Titration When Starting Intuniv
You do not need to titrate or adjust Strattera (atomoxetine) when starting Intuniv (guanfacine), as these medications can be safely combined without dose modification of the existing atomoxetine regimen. 1
Key Clinical Considerations
No Pharmacokinetic Interaction
- Atomoxetine and guanfacine do not have clinically significant drug-drug interactions that would require dose adjustment of either medication. 1
- Unlike CYP2D6 inhibitors (such as duloxetine or paroxetine) which significantly increase atomoxetine exposure and require careful dose titration, guanfacine does not affect atomoxetine metabolism. 2, 3
- Atomoxetine is primarily metabolized by CYP2D6, while guanfacine does not inhibit or induce this enzyme system. 3
Initiation Strategy for Intuniv
- Start guanfacine at 1 mg once daily and titrate by 1 mg per week based on response and tolerability, with a target dose range of 0.05 to 0.12 mg/kg/day or 1 to 7 mg/day. 1
- Continue the established atomoxetine dose without modification during guanfacine initiation. 1
Essential Monitoring Requirements
- Measure blood pressure and pulse at baseline, after each guanfacine dose adjustment, and at least monthly during maintenance therapy. 2
- Both medications can cause cardiovascular effects, though through different mechanisms—atomoxetine increases heart rate and blood pressure modestly, while guanfacine (an alpha-2 agonist) typically lowers blood pressure. 4, 5
- Monitor for sustained clinical hypertension or hypotension, as the net cardiovascular effect of the combination may vary by patient. 2
Common Pitfalls to Avoid
Overlapping Adverse Effects
- Both medications can cause sedation, particularly during the initial titration phase of guanfacine. 1
- Atomoxetine commonly causes gastrointestinal symptoms (nausea, decreased appetite, abdominal pain) and these may be compounded during the adjustment period. 4, 6
- Warn patients about potential additive sedation effects, especially during the first few weeks of guanfacine initiation. 1
Discontinuation Considerations
- If guanfacine needs to be discontinued, it should be tapered gradually to avoid rebound hypertension, whereas atomoxetine can be stopped abruptly without discontinuation syndrome. 7
- Atomoxetine does not cause symptom rebound upon discontinuation. 6, 7
Trial Duration
- Allow at least 6-8 weeks to evaluate the full efficacy and tolerability of the combination therapy. 7
- Guanfacine requires gradual titration over several weeks to reach therapeutic doses, and full therapeutic effects may not be apparent immediately. 1
Clinical Context for Combination Therapy
When This Combination Is Appropriate
- This combination is particularly useful for patients with ADHD who have incomplete response to atomoxetine monotherapy or who have comorbid conditions such as tics or anxiety. 4, 6
- Guanfacine can provide additional benefit for hyperactivity and impulsivity symptoms while atomoxetine addresses inattention. 1
- Both medications are non-stimulants with negligible abuse potential, making this combination suitable for patients at risk for substance abuse. 4, 5