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Palpitations and Asthenia Associated with Venlafaxine in a CYP2D6 Poor Metabolizer and CYP2C19 Intermediate
Sofia Garcia1, Michael Schuh2, Anvir Cheema3
1College of Pharmacy, University of Florida, Gainesville, FL, USA.
Abstract:
Cardiotoxicity has been extensively reported in venlafaxine (VEN) overdoses. Asthenia is also among the common side effects described for this antidepressant. VEN is metabolized mainly by CYP2D6 and to a minor extent by CYP2C19 to the major active metabolite O-desmethylvenlafaxine (ODV). Altered pharmacokinetic parameters in patients with polymorphisms in the CYP2D6 and CYP2C19 genes that result in decreased enzymatic activity have been documented. Here we describe a patient case of VEN associated palpitations and asthenia. The patient takes VEN extended release 150 mg twice daily. Genotyping confirmed the patient is a poor metabolizer for CYP2D6 and an intermediate metabolizer for CYP2C19. We propose that the palpitations and asthenia are related to sustained VEN exposure due to reduced metabolism.
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