Duloxetine-associated tachycardia

To report a case of symptomatic tachycardia that was successfully treated with propranolol in a patient receiving duloxetine.

A 26-year-old man presented with episodes of fatigue, tachycardia, diaphoresis, and chest pain approximately 2 months after the initiation of duloxetine 20 mg/day for dysthymic disorder. Cardiac workup including echocardiogram, exercise treadmill testing, and Holter monitoring was negative, except for tachycardia (heart rate 110-120 beats/min). Duloxetine was withheld, and the patient's heart rate returned to normal in less than a week. Duloxetine was restarted at the same dosage, and tachycardia returned within 2 days. Propranolol was added to the treatment regimen to lower the heart rate. Because of therapeutic failure of other antidepressants, duloxetine was continued because of its beneficial effects on mood.

One published case report describing tachycardia in association with duloxetine in 2 heart failure patients was found in a MEDLINE search (1966-July 2008). Increased blood pressure and heart rate have been reported in duloxetine trials. The proposed mechanism for duloxetine-induced tachycardia is its effects on norepinephrine, which impact the cardiovascular system. Use of the Naranjo probability scale indicated duloxetine as a probable cause of this patient's tachycardia.

Clinicians should be aware of the possibility of clinically significant tachycardia in patients receiving duloxetine, even in low doses.