Interaction between Omeprazole and Gliclazide in Relation to CYP2C19 Phenotype

Tanja Dujic (Lead / Corresponding author), Sandra Cvijic, Amar Elezovic, Tamer Bego, Selma Imamovic Kadric, Maja Malenica, Alisa Elezovic, Ewan R. Pearson, Aida Kulo

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The antidiabetic drug gliclazide is partly metabolized by CYP2C19, the main enzyme involved in omeprazole metabolism. The aim of the study was to explore the interaction between omeprazole and gliclazide in relation to CYP2C19 phenotype using physiologically based pharmacokinetic (PBPK) modeling approach. Developed PBPK models were verified using in vivo pharmacokinetic profiles obtained from a clinical trial on omeprazole-gliclazide interaction in healthy volunteers, CYP2C19 normal/rapid/ultrarapid metabolizers (NM/RM/UM). In addition, the association of omeprazole cotreatment with gliclazide-induced hypoglycemia was explored in 267 patients with type 2 diabetes (T2D) from the GoDARTS cohort, Scotland. The PBPK simulations predicted 1.4-1.6-fold higher gliclazide area under the curve (AUC) after 5-day treatment with 20 mg omeprazole in all CYP2C19 phenotype groups except in poor metabolizers. The predicted gliclazide AUC increased 2.1 and 2.5-fold in intermediate metabolizers, and 2.6- and 3.8-fold in NM/RM/UM group, after simulated 20-day dosing with 40 mg omeprazole once and twice daily, respectively. The predicted results were corroborated by findings in patients with T2D which demonstrated 3.3-fold higher odds of severe gliclazide-induced hypoglycemia in NM/RM/UM patients concomitantly treated with omeprazole. Our results indicate that omeprazole may increase exposure to gliclazide and thus increase the risk of gliclazide-associated hypoglycemia in the majority of patients.

Original languageEnglish
Article number367
Number of pages21
JournalJournal of Personalized Medicine
Issue number5
Publication statusPublished - 3 May 2021


  • omeprazole
  • gliclazide
  • CYP2C19
  • physiologically based pharmacokinetic modeling
  • drug-drug interaction
  • drug–drug–gene interaction
  • type-2 diabetes
  • adverse drug reaction
  • hypoglycemia


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