Effects of esomeprazole on the pharmacokinetics of other drugs: Protease inhibitors: Omeprazole has been reported to interact with some protease inhibitors. The clinical importance and the mechanisms behind these reported interactions are not always known. Increased gastric pH during omeprazole treatment may change the absorption of these protease inhibitors. Other possible interaction mechanisms are via inhibition of CYP2C19.
For Atazanavir and nelfinavir, decreased serum levels have been reported when given together with omeprazole and concomitant administration is not recommended. Co-administration of omeprazole (40 mg once daily) with Atazanavir 300 mg/ritonavir 100 mg to healthy volunteers resulted in a substantial reduction in Atazanavir exposure (approximately 75% decrease in AUC, Cmax and Cmin). Increasing the Atazanavir dose to 400 mg did not compensate for the impact of omeprazole on Atazanavir exposure. The co-administration of omeprazole (20 mg qd) with Atazanavir 400 mg/ritonavir 100 mg to healthy volunteers resulted in a decrease of approximately 80% in the Atazanavir exposure as compared with exposure observed with Atazanavir 300 mg/ritonavir 100 mg qd without omeprazole 20 mg qd. Co-administration of omeprazole (40 mg qd) reduced mean nelfinavir AUC, Cmax and Cmin by 36-39% and mean AUC, Cmax and Cmin for the pharmacologically active metabolite M8 was reduced by 75-92%. Due to the similar Pharmacodynamic effects and pharmacokinetic properties of omeprazole and esomeprazole, concomitant administration with esomeprazole and Atazanavir is not recommended and concomitant administration with esomeprazole and nelfinavir is contraindicated.
Methotrexate: When given together with PPIs, methotrexate levels have been reported to increase in some patients. In high-dose methotrexate administration a temporary withdrawal of esomeprazole may need to be considered.
Tacrolimus: Concomitant administration of esomeprazole has been reported to increase the serum levels of tacrolimus. A reinforced monitoring of tacrolimus concentrations as well as renal function (creatinine clearance) should be performed, and dosage of tacrolimus adjusted if needed.
Medicinal products metabolized by CYP2C19: Esomeprazole inhibits CYP2C19, the major esomeprazole-metabolizing enzyme. Thus, when esomeprazole is combined with drugs metabolized by CYP2C19, such as diazepam, citalopram, imipramine, clomipramine, phenytoin etc., the plasma concentrations of these drugs may be increased and a dose reduction could be needed. This should be considered especially when prescribing esomeprazole for on-demand therapy.
Diazepam: Concomitant administration of 30 mg esomeprazole resulted in a 45% decrease in clearance of the CYP2C19 substrate diazepam.
Phenytoin: Concomitant administration of 40 mg esomeprazole resulted in a 13% increase in trough plasma levels of phenytoin in epileptic patients. It is recommended to monitor the plasma concentrations of phenytoin when treatment with esomeprazole is introduced or withdrawn.
Voriconazole: Omeprazole (40 mg once daily) increased voriconazole (a CYP2C19) substrate C and AUC by 15% and 41%, respectively.
Cilostazol: Omeprazole as well as esomeprazole act as inhibitors of CYP2C19. Omeprazole, given in doses of 40 mg to healthy subjects in a cross-over study, increased C and AUC for cilostazol by 18% and 26% respectively, and one of its active metabolites by 29% and 69% respectively.
Cisapride: In healthy volunteers, concomitant administration of 40 mg esomeprazole resulted in a 32% increase in area under the plasma concentration-time curve (AUC) and a 31% prolongation of elimination half-life (t1/2) but no significant increase in peak plasma levels of cisapride. The slightly prolonged QTc interval observed after administration of cisapride alone, was not further prolonged when cisapride was given in combination with esomeprazole.
Warfarin: Concomitant administration of 40 mg esomeprazole to warfarin-treated patients in a clinical trial showed that coagulation times were within the accepted range. However, post-marketing, a few isolated cases of elevated INR of clinical significance have been reported during concomitant treatment. Monitoring is recommended when initiating and ending concomitant esomeprazole treatment during treatment with warfarin or other coumarine derivatives.
Clopidogrel: Results in healthy subjects have shown a pharmacokinetic (PK)/Pharmacodynamic (PD) interaction between clopidogrel (300 mg loading dose/75 mg daily maintenance dose) and esomeprazole (40 mg p.o. daily) resulting in decreased exposure to the active metabolite of clopidogrel by an average of 40% and resulting in decreased maximum inhibition of (ADP induced) platelet aggression by an average of 14%.
When clopidogrel was given together with a fixed dose combination of esomeprazole 20 mg + ASA 81 mg compared to clopidogrel alone in a study in healthy subjects there was a decreased exposure by almost 40% of the active metabolite of clopidogrel. However, the maximum levels of inhibition (ADP induced) platelet aggregation in these subjects were the same in the clopidogrel and the clopidogrel + combined (esomeprazole + ASA) product groups. Inconsistent data on the clinical implications of a PK/PD interaction of esomeprazole in terms of major cardiovascular events have been reported from both observational and clinical studies. As a precaution concomitant use of clopidogrel should be discouraged.
Investigated medicinal products with no clinically relevant interaction: Amoxicillin and quinidine: Esomeprazole has been shown to have no clinically relevant effects on the pharmacokinetics of amoxicillin or quinidine.
Naproxen or rofecoxib: Studies evaluating concomitant administration of esomeprazole and neither naproxen or rofecoxib did not identify any clinically relevant pharmacokinetic interactions during short-term studies.
Effects of other medicinal products on the pharmacokinetics of esomeprazole: Medicinal products which inhibit CYP2C19 and/or CYP3A4: Esomeprazole is metabolised by CYP2C19 and CYP3A4. Concomitant administration of esomeprazole and a CYP3A4 inhibitor, clarithromycin (500 mg b.i.d.), resulted in a doubling of the exposure (AUC) to esomeprazole. Concomitant administration of esomeprazole and a combined inhibitor of CYP2C19 and CYP 3A4 may result in more than doubling of the esomeprazole exposure. The CYP2C19 and CYP3A4 inhibitor voriconazole increased omeprazole AUCτ by 280%. A dose adjustment of esomeprazole is not regularly required in either of these situations. However, dose adjustment should be considered in patients with severe hepatic impairment and if long-term treatment is indicated.
Medicinal products which induce CYP2C19 and/or CYP3A4: Drugs known to induce CYP2C19 or CYP3A4 or both (such as rifampicin and St. John's wort) may lead to decreased esomeprazole serum levels by increasing the esomeprazole metabolism.
Paediatric population: Interaction studies have been performing in adults.