Pharmacopsychiatry 2015; 25 - A32
DOI: 10.1055/s-0035-1557970

Effects of Proton Pump Inhibitors (PPI) on the serum concentrations of Venlafaxine

M Kuzin 1, S E Lammertz 2, B Stegmann 3, E Haen 3, G Gründer 1, M Paulzen 3
  • 1Department of Psychiatry, Psychotherapy and Psychosomatics, RWTH Aachen University, Aachen, Germany, and JARA
  • 2Translational Brain Medicine, University of Regensburg, Regensburg, Germany
  • 3Department of Psychiatry and Psychotherapy, Clinical Psychopharmacology, University of Regensburg, Regensburg, Germany

Objectives: Venlafaxine is metabolized by CYP2D6 to O-desmethylvenlafaxine (ODV) and by CYP3A4 to N-desmethylvenlafaxine (NDV). CYP2C19 is also involved in the formation of ODV. The PPIs omeprazole and pantoprazole inhibit CYP2C19 to a different extent. Aim of this study was to investigate the potential effects of both PPIs on serum levels of VEN and ODV. Methods: From a therapeutic drug monitoring (TDM) database, serum concentrations of VEN, ODV and the active moiety (VEN + ODV), were analyzed. Data from 120 patients were available and splitted into three groups: patients without PPI [noPPI], with pantoprazole [PANTO] or with omeprazole [OMEP] (n = 40 each). The ratio of (ODV/VEN) was calculated as a marker of the metabolizer status. For statistical comparison the Studentʼs t-test was used. Results: Differences in the ratio ODV/VEN were neither found between the PANTO and OMEP group (p = 0.659), nor between the noPPI group and the PPI groups (OMEP: p = 0.196; PANTO: p = 0.107). However, both PPI groups showed elevated levels of VEN compared with the noPPI group, OMEP (p = 0.037), PANTO (p = 0.042). Values of the active moiety were significantly higher in the OMEP group (p = 0.044). Conclusion: Both, omeprazole and pantoprazole led to a varying extent in increases of the serum concentrations of venlafaxine. The increase is driven by significantly higher levels of VEN rather than by increasing levels of ODV. This might be due to CYP2C19 blocking properties of both PPIs.