Drug Design, Development and Therapy (Aug 2020)

Therapeutic Drug Monitoring of Rivastigmine and Donepezil Under Consideration of CYP2D6 Genotype-Dependent Metabolism of Donepezil

  • Ortner M,
  • Stange M,
  • Schneider H,
  • Schröder C,
  • Buerger K,
  • Müller C,
  • Müller-Sarnowski F,
  • Diehl-Schmid J,
  • Förstl H,
  • Grimmer T,
  • Steimer W

Journal volume & issue
Vol. Volume 14
pp. 3251 – 3262

Abstract

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Marion Ortner,1 Marion Stange,1 Heike Schneider,1 Charlotte Schröder,2 Katharina Buerger,3 Claudia Müller,3 Felix Müller-Sarnowski,1 Janine Diehl-Schmid,1 Hans Förstl,1 Timo Grimmer1 ,* Werner Steimer2, * 1Department of Psychiatry and Psychotherapy, Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Munich, Germany; 2Institute for Clinical Chemistry and Pathobiochemistry, Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Munich, Germany; 3Institute for Stroke and Dementia Research (ISD), University of Munich, School of Medicine, Klinikum der Universität München, Munich, Germany*These authors contributed equally to this workCorrespondence: Marion Ortner Email [email protected]: The efficacy of acetylcholinesterase inhibitors (AChE-I) might depend on blood concentration. While rivastigmine metabolism is independent of the cytochrome P450 system, its isoenzymes, especially CYP2D6, metabolize donepezil. CYP2D6 polymorphisms can cause altered enzyme activity resulting in lower or higher than expected drug concentrations of donepezil.Objective: We investigated correlations between clinical efficacy and serum concentrations of rivastigmine and donepezil under special consideration of CYP 2D6 genotype or gene dose–dependent metabolism of donepezil.Methods: Serum concentrations of donepezil and rivastigmine were measured by liquid chromatography – tandem mass spectrometry (LC-MS/MS). Real-time quantitative polymerase chain reaction (PCR) and allele-specific PCR were performed to assess CYP2D6 genotype and gene dose.Results: Patients treated with rivastigmine (n=28) or donepezil (n=48) were included in the study. Both gene dose and metabolism type significantly predicted the level of donepezil serum concentration (p=0.019 and p=0.013, respectively). In the rivastigmine group, changes of the word list delayed recall subtest before treatment and under stable medication were significantly associated with rivastigmine serum levels (β=0.465; p=0.018). Drug serum concentrations were outside the recommended range in a substantial percentage of participants, which might have contributed to poor correlations between changes in cognitive measures and drug concentrations. Donepezil serum concentrations significantly depended on CYP2D6 gene dose.Conclusion: Testing AChE-I serum concentration should be considered in patients without clinical response to treatment or those with severe side effects. Patients with donepezil drug levels outside the recommended range might additionally profit from CYP2D6 genotyping or treatment with an AChE-I independent of CYP metabolism.Keywords: Alzheimer’s disease, cytochrome P-450 enzymes, genetic polymorphism, therapeutic drug monitoring, mass spectrometry

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