Pharmacopsychiatry 2022; 55(06): 315
DOI: 10.1055/s-0042-1757673
Abstracts | AGNP/DGBP
P6 Therapeutic drug treatment

Bariatric surgery: impact on oral aripiprazole and fluoxetine bioavailability – A clinical case

Authors

  • Maxim Kuzin

    1   Private Psychiatric Hospital and Academic Teaching Hospital of the University of Zurich, Oetwil am See, Switzerland

  • Georgios Schoretsanitis

    2   Department of Psychiatry, Psychotherapy and Psychosomatics, University Clinic Zurich, Switzerland

  • Markus Götschi

    1   Private Psychiatric Hospital and Academic Teaching Hospital of the University of Zurich, Oetwil am See, Switzerland

  • Fabian Gardin

    1   Private Psychiatric Hospital and Academic Teaching Hospital of the University of Zurich, Oetwil am See, Switzerland

  • Wolfram Kawohl

    1   Private Psychiatric Hospital and Academic Teaching Hospital of the University of Zurich, Oetwil am See, Switzerland

  • Franziskos Xepapadakos

    1   Private Psychiatric Hospital and Academic Teaching Hospital of the University of Zurich, Oetwil am See, Switzerland
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Introduction Bioavailability alterations for pharmacological agents following bariatric operations have been previously reported, although they may vary based on the medication. Here we report the post- bariatric impact of the Roux-en-Y gastric bypass (RYGB) on the bioavailability of aripiprazole using therapeutic drug monitoring (TDM).

Methods TDM was performed in a female inpatient that had received a RYGB in 2014 and was treated with aripiprazole (15 mg/d) and fluoxetine (80 mg/d, dispersible tablet). A switch to the liquid form of aripiprazole was made as a part of therapy optimization.

Results During intake of pills, we assessed subtherapeutic concentrations of aripiprazole (mean 71.8 ng/mL), but supratherapeutic concentration of fluoxetine (fluoxetine+ norfluoxetine: 746 (368.4+377.6) ng/mL). Switching to aripiprazole on a syrup basis under the same daily aripiprazole dosage led four days later to an increase in serum-concentration by 61.6% (116.6 ng/mL), representing an increase of the concentration to dose ratio (C/D) of aripiprazole from the initial range of 4.5-5.1 to 7.8 (ng/mL/mg).

Conclusion A reduction of the daily dosage of aripiprazole up to 50% is recommended under simultaneous prescription of CYP2D6 inhibitors, e.g. fluoxetine. The low C/D of aripiprazole despite the inhibiting effects of fluoxetine may be due to post-RYGB malabsorption. This hypothesis is further supported by variations of the measured serum concentrations, depending on the mode of drug delivery. This case underlines the importance of TDM in dose selection to enhance safety and efficacy outcomes.


Conflict of interest

MK received travel grants from Sunovion Pharmaceutical (Basel, Switzerland) and Otsuka Pharmaceutical (Glattbrugg, Switzerland). He also received a travel grant, particapted and obtained a grant at speaker board of Lundbeck (Zurich, Switzerland).

Publication History

Article published online:
08 November 2022

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