What should be done for an ADHD patient who just started atomoxetine (Strattera) and is experiencing dizziness?

Management of Dizziness in an ADHD Patient Starting Atomoxetine

Dizziness is a common adverse effect of atomoxetine that typically occurs during initial treatment or dose escalation; continue the medication at the current dose without increasing, monitor blood pressure and pulse in both seated and standing positions, and reassure the patient that this side effect is usually transient and resolves within 1-2 weeks. 1, 2, 3

Understanding the Problem

• Dizziness is explicitly listed as a common adverse effect of atomoxetine, occurring significantly more frequently than with placebo in adult clinical trials 3, 4
• This side effect is particularly common when dosage is increased too rapidly, suggesting your patient may be experiencing a normal initial response to the medication 1
• The FDA label specifically documents orthostatic hypotension and syncope as potential cardiovascular effects of atomoxetine, with 1.8% of pediatric patients experiencing orthostatic hypotension in short-term trials 2

Immediate Management Steps

1. Cardiovascular Assessment

• Measure blood pressure and pulse at baseline and in both seated and standing positions to detect orthostatic changes, as atomoxetine can cause orthostatic hypotension 2, 1
• The FDA recommends that pulse and blood pressure should be measured following atomoxetine dose increases and periodically while on therapy to detect clinically important increases 2
• Atomoxetine causes modest increases in heart rate (mean 5 beats/minute in extensive metabolizers, 9.4 beats/minute in poor metabolizers) and blood pressure that are generally well tolerated 2, 5

2. Dosing Strategy

• Do not increase the dose further until dizziness resolves; the current dose should be maintained for at least 7-14 days before any upward titration 1
• If the patient is on once-daily dosing, consider splitting the dose into two evenly divided doses (morning and evening) to reduce peak plasma concentrations and minimize side effects 1, 5, 3
• Evening-only dosing is also an option if morning dizziness is particularly problematic 1

3. Patient Education and Monitoring

• Counsel the patient that dizziness is typically transient and resolves within the first 1-2 weeks of treatment as tolerance develops to this side effect 1, 3, 4
• Advise the patient to rise slowly from sitting or lying positions to minimize orthostatic symptoms 2
• Atomoxetine should be used with caution in any condition that may predispose patients to hypotension or conditions associated with abrupt heart rate or blood pressure changes 2

When to Consider Dose Reduction or Discontinuation

• If dizziness is severe, persistent beyond 2 weeks, or accompanied by syncope (fainting), reduce the dose or temporarily discontinue atomoxetine 2
• In adult registration studies, 0.2% of patients experienced orthostatic hypotension and 0.8% experienced syncope, warranting careful monitoring 2
• The discontinuation rate due to adverse events in atomoxetine-treated adults was 7.8-9.3% versus 4.3% for placebo, with dizziness being one of the contributing factors 3, 4

Important Pharmacogenetic Consideration

• Approximately 7% of Caucasians and 2% of African Americans are poor CYP2D6 metabolizers, resulting in 10-fold higher drug exposure and significantly more adverse effects including dizziness 1
• Poor metabolizers experience higher mean increases in blood pressure (diastolic: 4.21 vs 2.13 mm Hg; systolic: 2.75 vs 2.40 mm Hg) compared to extensive metabolizers 2
• If dizziness is severe and persistent, consider that the patient may be a poor metabolizer and may require a lower maintenance dose 1, 5

Timeline for Therapeutic Effect

• Reassure the patient that atomoxetine requires 6-12 weeks to achieve full therapeutic effect for ADHD symptoms, so early side effects should not prompt premature discontinuation 1, 5, 6
• The duration of action extends throughout waking hours with once-daily morning dosing, providing "around-the-clock" symptom coverage 1, 6

Common Pitfall to Avoid

• Do not discontinue atomoxetine prematurely due to transient dizziness; most patients develop tolerance to this side effect while maintaining therapeutic benefit for ADHD 3, 4
• Unlike stimulants that work within days, atomoxetine's delayed onset means patients must tolerate initial side effects to reach the therapeutic window 1, 5