Dicloxacillin is an inducer of intestinal P-glycoprotein but neither dicloxacillin nor flucloxacillin increases the risk of stroke/systemic embolism in direct oral anticoagulant users

Ditte B. Iversen, Ann Cathrine Dalgård Dunvald, Martin Thomsen Ernst, Shahab Abtahi, Patrick Souverein, Olaf Klungel, Glenn Brøde Jeppesen, Flemming Nielsen, Kim Brøsen, Helen S. Hammer, Oliver Pötz, Per Damkier, Erkka Järvinen, Anton Pottegård, Tore B. Stage*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Aim

We aimed to assess if dicloxacillin/flucloxacillin reduces the therapeutic efficacy of direct oral anticoagulants (DOACs) and the underlying molecular mechanism. 


Methods

In a randomized, crossover study, we assessed whether dicloxacillin reduces oral absorption of drugs through P-glycoprotein (P-gp) during 10 and 28 days of treatment. To study the impact of dicloxacillin/flucloxacillin on intestinal and hepatic expression of P-gp in vitro, we usd LS174T cells and 3D spheroids of primary human hepatocytes. Finally, we used nationwide Danish health registries and the UK's Clinical Practice Research Datalink to estimate hazard ratios (HRs) for the risk of stroke and systemic embolism following dicloxacillin/flucloxacillin exposure among DOAC users, using phenoxymethylpenicillin and amoxicillin as active comparators. 


Results

Dicloxacillin reduced the area under the curve of dabigatran to a geometric mean ratio 10 days of 0.67 (95% confidence interval [CI]: 0.42–1.1) and geometric mean ratio 28 days of 0.72 (95% CI: 0.39–1.4), suggesting reduced oral absorption via increased P-gp expression. In vitro, dicloxacillin raised P-gp expression in both intestinal and liver cells, while flucloxacillin only affected liver cells. In the pharmacoepidemiologic study, dicloxacillin and flucloxacillin were not associated with increased risk of stroke/systemic embolism (dicloxacillin vs. phenoxymethylpenicillin HR: 0.93, 95% CI: 0.72–1.2; flucloxacillin vs. amoxicillin HR: 0.89, 95% CI: 0.51–1.5). 


Conclusions

Dicloxacillin increases expression of intestinal P-gp, leading to reduced oral absorption of dabigatran. However, concomitant use of dicloxacillin/flucloxacillin was not associated with stroke and systemic embolism among DOAC users, suggesting no clinical impact from the drug–drug interaction between dicloxacillin/flucloxacillin and DOACs.

Original languageEnglish
JournalBritish Journal of Clinical Pharmacology
Volume90
Issue number12
Pages (from-to)3252-3262
ISSN0306-5251
DOIs
Publication statusPublished - Dec 2024

Keywords

  • antibiotics
  • direct oral anticoagulants
  • drug–drug interactions
  • P-glycoprotein transporter
  • stroke
  • systemic embolism
  • Dicloxacillin/administration & dosage
  • ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
  • Embolism/prevention & control
  • Administration, Oral
  • Humans
  • Middle Aged
  • Floxacillin/administration & dosage
  • Male
  • Hepatocytes/drug effects
  • Anticoagulants/administration & dosage
  • Cross-Over Studies
  • Drug Interactions
  • Stroke/prevention & control
  • Dabigatran/administration & dosage
  • Aged, 80 and over
  • Female
  • Aged

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