Can Strattera (atomoxetine) cause tachycardia in patients, particularly those with pre-existing heart conditions or taking other medications?

Can Strattera Cause Tachycardia?

Yes, Strattera (atomoxetine) can cause tachycardia and increases in heart rate, particularly in patients who are poor CYP2D6 metabolizers or those taking CYP2D6 inhibitors. 1

Cardiovascular Effects on Heart Rate

Atomoxetine causes clinically significant increases in heart rate that require monitoring. The FDA label documents that:

• In pediatric placebo-controlled trials, 23.4% of atomoxetine patients experienced heart rate increases ≥20 bpm compared to 11.5% on placebo 1
• Tachycardia was identified as an adverse event in 0.3% of pediatric patients on atomoxetine versus 0% on placebo 1
• In adult trials, 1.5% experienced tachycardia as an adverse event compared to 0.5% on placebo 1
• Mean heart rate increases were 5 beats/minute in extensive metabolizers (EM) and 9.4 beats/minute in poor metabolizers (PM) 1

High-Risk Populations

Poor CYP2D6 metabolizers face substantially higher cardiovascular risks. These patients experience:

• Mean heart rate increases of 11 beats/minute versus 7.5 beats/minute in extensive metabolizers 1
• Higher mean increases in diastolic blood pressure (4.21 versus 2.13 mm Hg) 1
• Higher mean increases in systolic blood pressure (2.75 versus 2.40 mm Hg) 1
• The heart rate and blood pressure effects could be clinically important in some PM patients 1

A case report documented a patient presenting with syncope, orthostatic hypotension, and tachycardia related to atomoxetine use 2

Contraindications and Pre-existing Heart Conditions

Atomoxetine should not be used in patients with severe cardiac or vascular disorders whose condition would deteriorate with clinically important increases in blood pressure or heart rate. 1

The FDA specifically states that atomoxetine:

• Generally should not be used in children or adolescents with known serious structural cardiac abnormalities, cardiomyopathy, serious heart rhythm abnormalities, or other serious cardiac problems that may increase vulnerability to noradrenergic effects 1
• Requires consideration to not treat adults with clinically significant cardiac abnormalities 1
• Should be used with caution in patients with hypertension, tachycardia, or cardiovascular or cerebrovascular disease 1

Drug Interactions Increasing Risk

Concomitant use with strong CYP2D6 inhibitors significantly increases tachycardia risk. 1

CYP2D6 inhibitors (such as paroxetine, fluoxetine, quinidine) cause changes in atomoxetine pharmacokinetics similar to those in poor metabolizers, resulting in higher plasma concentrations and increased cardiovascular effects 3

Required Monitoring Protocol

Pulse and blood pressure must be measured at baseline, after dose increases, and periodically during therapy. 1

Before initiating atomoxetine, patients should have:

• Careful history including assessment for family history of sudden death or ventricular arrhythmia 1
• Physical examination to assess for cardiac disease 1
• Further cardiac evaluation (ECG and echocardiogram) if findings suggest cardiac disease 1

Patients developing exertional chest pain, unexplained syncope, or symptoms suggestive of cardiac disease during treatment should undergo prompt cardiac evaluation. 1

Serious Cardiovascular Events Reported

Beyond tachycardia, sudden deaths, stroke, and myocardial infarction have been reported in adults taking atomoxetine at usual doses. 1

Case reports document:

• Myocardial infarction in a young woman on atomoxetine 4
• Life-threatening QT prolongation with bradycardia, inverted T waves, multiple PVCs, and Takotsubo cardiomyopathy in an 11-year-old boy after 2 years of atomoxetine use 5
• Seizure and mild QRS widening following atomoxetine overdose 6

Clinical Implications

The noradrenergic mechanism of atomoxetine directly explains the tachycardia and cardiovascular effects. As a selective norepinephrine reuptake inhibitor, atomoxetine increases noradrenergic tone, which elevates heart rate and blood pressure 3, 2

Atomoxetine should be discontinued if clinically significant tachycardia or other cardiovascular symptoms develop, and patients should not be restarted without thorough cardiac evaluation 1