Moderate
Probable
Description
Omeprazole inhibits CYP2C19 and weakly inhibits CYP3A4, leading to modest increases in tacrolimus exposure particularly in CYP2C19 poor metabolisers.
Mécanisme
Tacrolimus is a minor CYP2C19 substrate; omeprazole's potent CYP2C19 inhibition reduces a secondary metabolic pathway, with the magnitude dependent on the patient's CYP2C19 genotype.
Signification clinique
In CYP2C19 poor metabolisers, tacrolimus trough increases of 20–40% have been reported; this is generally less pronounced than with strong CYP3A4 inhibitors.
Prise en charge
Monitor tacrolimus trough levels when initiating or discontinuing omeprazole, particularly in patients with known or suspected CYP2C19 poor-metaboliser status; pantoprazole is a lower-risk alternative.