Pharmacogenetic determinant of the drug interaction between tacrolimus and omeprazole

CYP3A4*1B but Not CYP3A5*3 as Determinant of Long-Term Tacrolimus Dose Requirements in Spanish Solid Organ Transplant Patients

Tacrolimus (TAC) is a commonly used immunosuppressive drug in solid organ transplantation. Pharmacogenetics has been demonstrated before to be decisive in TAC pharmacotherapy. The CYP3A5*3 variant has been reported to be the main determinant of TAC dose requirements; however, other polymorphisms have also proven to be influential, especially in CYP3A5 non-expressor patients. The aim of this study is to evaluate the influence of genetic polymorphisms in TAC therapy in a cohort of Spanish transplant recipients. Genetic analysis including ten polymorphic variants was performed, and demographic and clinical data and pharmacotherapy of 26 patients were analyzed. No significant differences were found in weight-adjusted dose between CYP3A5 expressors and non-expressors (0.047 mg/kg vs. 0.044 mg/kg), while they were found for carriers of the CYP3A4*1B allele (0.101 mg/kg; p < 0.05). The results showed that patients with at least one CYP3A4*1B allele had a higher TAC dose and lower blood concentration. Dose-adjusted TAC blood levels were also lower in CYP3A4*1B carriers compared to non-carriers (0.72 ng/mL/mg vs. 2.88 ng/mL/mg). These results support the independence of CYP3A5*3 and CYP3A4*1B variants as determinants of dose requirements despite the linkage disequilibrium present between the two. The variability in genotype frequency between ethnicities may be responsible for the discrepancy found between studies.

Assessment of omeprazole and famotidine effects on the pharmacokinetics of tacrolimus in patients following kidney transplant-randomized controlled trial

Tacrolimus is metabolized in the liver with the participation of the CYP3A4 and CYP3A5 enzymes. Proton pump inhibitors are used in kidney transplant patients to prevent duodenal and gastric ulcer disease due to glucocorticoids. Omeprazole, unlike famotidine, is a substrate and inhibitor of the enzymes CYP2C19, CYP3A4, CYP3A5. The aim of this study was to compare the impact of omeprazole and famotidine on the pharmacokinetics of tacrolimus. A randomized, non-blinded study involving 22 stabilized adult kidney transplant patients was conducted. Patients received the standard triple immunosuppression regimen and omeprazole 20 mg (n = 10) or famotidine 20 mg (n = 12). The study material consisted of blood samples in which tacrolimus concentrations were determined using the Chemiluminescent Microparticle Immuno Assay method. A single administration of omeprazole increased tacrolimus concentrations at 2 h (day 2) = 11.90 ± 1.59 ng/mL vs. 2 h (day 1 - no omeprazole administration) = 9.40 ± 0.79 ng/mL (p = 0.0443). AUC0-6 amounted to 63.07 ± 19.46 ng × h/mL (day 2) vs. 54.23 ± 10.48 ng × h/mL (day 1), (p = 0.0295). AUC2-6 amounted to 44.32 ± 11.51 ng × h/mL (day 2) vs. 38.68 ± 7.70 ng × h/mL (day 1), (p = 0.0130). Conversely, no significant changes in values of pharmacokinetic parameters were observed for famotidine. Omeprazole significantly increases blood exposure of tacrolimus. The administration of famotidine instead of omeprazole seems safer for patients following kidney transplantation. Clinical Trial Registration: clinicaltrials.gov, identifier NCT05061303.

Dosage optimization of tacrolimus based on the glucocorticoid dose and pharmacogenetics in adult patients with systemic lupus erythematosus

BACKGROUND

The purpose of the study was to develop a genotype-incorporated population pharmacokinetic (PPK) model of tacrolimus (TAC) in adults with systemic lupus erythematosus (SLE) to investigate the factors influencing TAC pharmacokinetics and to develop an individualized dosing regimen based on the model. In addition, a non-genotype-incorporated model was also established to assess its predictive performance compared to the genotype-incorporated model.

METHODS

A total of 365 trough concentrations from 133 adult SLE patients treated with TAC were collected to develop a genotype-incorporated PPK model and a non-genotype-incorporated PPK model of TAC using a nonlinear mixed-effects model (NONMEM). External validation of the two models was performed using data from an additional 29 patients. Goodness-of-fit diagnostic plots, bootstrap method, and normalized predictive distribution error test were used to validate the predictive performance and stability of the final models. The goodness-of-fit of the two final models was compared using the Akaike information criterion (AIC). The dosing regimen was optimized using Monte Carlo simulations based on the developed optimal model.

RESULTS

The typical value of the apparent clearance (CL/F) of TAC estimated in the final genotype-incorporated model was 14.3 L h-1 with inter-individual variability of 27.6%. CYP3A5 polymorphism and coadministered medication were significant factors affecting TAC-CL/F. CYP3A5 rs776746 GG genotype carriers had only 77.3% of the TAC-CL/F of AA or AG genotype carriers. Omeprazole reduced TAC-CL/F by 3.7 L h-1 when combined with TAC, while TAC-CL/F increased nonlinearly as glucocorticoid dose increased. Similar findings were demonstrated in the non-genotype-incorporated PPK model. Comparing these two models, the genotype-incorporated PPK model was superior to the non-genotype-incorporated PPK model (AIC = 643.19 vs. 657.425). Monte Carlo simulation based on the genotype-incorporated PPK model indicated that CYP3A5 rs776746 AA or AG genotype carriers required a 1/2-1 fold higher dose of TAC than GG genotype carriers to achieve the target concentration. And as the daily dose of prednisone increases, the dose of TAC required to reach the target concentration increases appropriately.

CONCLUSIONS

We developed the first pharmacogenetic-based PPK model of TAC in adult patients with SLE and proposed a dosing regimen based on glucocorticoid dose and CYP3A5 genotype according to the model, which could facilitate individualized dosing for TAC.

Safety analysis of co-administering tacrolimus and omeprazole in renal transplant recipients - A review

Tacrolimus is a calcineurin inhibitor used to prevent rejection in allogenic solid organ transplant recipients, which is metabolized in the liver with cytochrome P450 isoforms 3A4 and 3A5 (CYP3A4, CYP3A5). In turn, proton pump inhibitors (PPIs), such as Omeprazole - a substrate and inhibitor of CYP2C19 and CYP3A4 enzymes - are administered to kidney transplant patients in order to prevent duodenal and gastric ulcer disease, associated with the glucocorticoid treatment. Simultaneous administration of both drugs in renal patients has the potential to trigger drug interactions. In fact, there are several mechanisms which may impact the pharmacokinetics of tacrolimus. Inhibition of the CYP2C19 isoform may suppress the metabolism of omeprazole, subsequently altering its metabolic pathway to be metabolized by the CYP3A4 enzyme in order to maintain adequate biotransformation. Therefore, the competition for CYP3A4 may affect the metabolism of tacrolimus and result in its increased plasma concentrations, as well as in adverse reactions. Another mechanism has been related to the genetic polymorphism of the CYP2C19 isoform. Since all these interactions may lead to dysfunctions of the transplanted kidney, it seems significant to eliminate their consequences, for instance via the administration of drugs which are neither substrates, nor inhibitors of the CYP3A4 enzyme. Finally, the nephrotoxic effect of omeprazole should also be accounted for. Bearing in mind the aforementioned observations, the aim of the presented paper was to review the available studies addressing the effect of omeprazole on the pharmacokinetics of tacrolimus.

Importance of Pharmacogenetics and Drug-Drug Interactions in a Kidney Transplanted Patient

Tacrolimus (TAC) is a narrow-therapeutic-range immunosuppressant drug used after organ transplantation. A therapeutic failure is possible if drug levels are not within the therapeutic range after the first year of treatment. Pharmacogenetic variants and drug-drug interactions (DDIs) are involved. We describe a patient case of a young man (16 years old) with a renal transplant receiving therapy including TAC, mycophenolic acid (MFA), prednisone and omeprazole for prophylaxis of gastric and duodenal ulceration. The patient showed great fluctuation in TAC blood concentration/oral dose ratio, as well as pharmacotherapy adverse effects (AEs) and frequent diarrhea episodes. Additionally, decreased kidney function was found. A pharmacotherapeutic follow-up, including pharmacogenetic analysis, was carried out. The selection of the genes studied was based on the previous literature (CYP3A5, CYP3A4, POR, ABCB1, PXR and CYP2C19). A drug interaction with omeprazole was reported and the nephrologist switched to rabeprazole. A lower TAC concentration/dose ratio was achieved, and the patient's condition improved. In addition, the TTT haplotype of ATP Binding Cassette Subfamily B member 1 (ABCB1) and Pregnane X Receptor (PXR) gene variants seemed to affect TAC pharmacotherapy in the studied patient and could explain the occurrence of long-term adverse effects post-transplantation. These findings suggest that polymorphic variants and co-treatments must be considered in order to achieve the effectiveness of the immunosuppressive therapy with TAC, especially when polymedicated patients are involved. Moreover, pharmacogenetics could influence the drug concentration at the cellular level, both in lymphocyte and in renal tissue, and should be explored in future studies.

Investigation of pharmacologic interactions between omeprazole and tacrolimus in a membranous nephropathy patient with CYP3A5 nonexpresser: a case report

Tacrolimus has been widely used in membranous nephropathy in recent years. The drug interactions of the coadministration of tacrolimus with omeprazole in CYP3A5 nonexpresser membranous nephropathy patients have not been demonstrated. Here, we report an idiopathic membranous nephropathy patient who was with CYP2C19*2/*2, CYP3A5*3/*3 (nonexpresser) and ABCB1 (3435 TT, 1236 computed tomography, 2677 TT) genotype requiring treatment with tacrolimus and omeprazole and found to have fluctuating metabolism of tacrolimus. This study shows that tacrolimus and omeprazole have pharmacologic drug interactions in CYP3A5 nonexpressers, implying that the CYP3A and ABCB1 gene mutations linked to tacrolimus metabolism may alter tacrolimus levels in the blood. The observed concentrations of tacrolimus were decreased after the discontinuation of omeprazole therapy. It demonstrates that, in addition to genotype, clinical covariates, such as omeprazole are important when it comes to better understanding and prediction of tacrolimus dosage. It is deemed necessary to monitor tacrolimus blood concentrations and make dose adjustments when patients were coadministered with omeprazole.

Pantoprazole Does not Affect Serum Trough Levels of Tacrolimus and Everolimus in Liver Transplant Recipients

Background: Liver transplant recipients are frequently treated with proton pump inhibitors. Drug interactions have been described especially with respect to omeprazole. Due to the lower binding capacity of pantoprazole to CYP2C19 this drug became preferred and became the most used proton pump inhibitor in Germany. The data on the influence of pantoprazole on immunosuppressive drugs in liver transplant recipients a very scarce.

Methods: The authors performed a single center analysis in liver transplant recipients on the effect of pantoprazole on the serum trough levels of different immunosuppressants. The trough levels were compared over a period of 1 year before and after start or stop of a continuous oral co-administration of 40 mg pantoprazole once daily.

Results: The serum trough levels of tacrolimus (n = 30), everolimus (n = 7), or sirolimus (n = 3) remain constant during an observation period of at least 1 year before and after co-administration of pantoprazole. None of the included patients needed a change of dosage of the observed immunosuppressants during the observation period.

Conclusions: The oral co-administration of pantoprazole is safe in immunosuppressed liver transplant recipients according to the serum trough levels of tacrolimus, everolimus, and sirolimus. This analysis provides first data on the influence of pantoprazole on immunosuppressive drugs in liver transplant recipients.

Complex Drug-Drug-Gene-Disease Interactions Involving Cytochromes P450: Systematic Review of Published Case Reports and Clinical Perspectives

Drug pharmacokinetics (PK) is influenced by multiple intrinsic and extrinsic factors, among which concomitant medications are responsible for drug-drug interactions (DDIs) that may have a clinical relevance, resulting in adverse drug reactions or reduced efficacy. The addition of intrinsic factors affecting cytochromes P450 (CYPs) activity and/or expression, such as genetic polymorphisms and diseases, may potentiate the impact and clinical relevance of DDIs. In addition, greater variability in drug levels and exposures has been observed when such intrinsic factors are present in addition to concomitant medications perpetrating DDIs. This variability results in poor predictability of DDIs and potentially dramatic clinical consequences. The present review illustrates the issue of complex DDIs using systematically searched published case reports of DDIs involving genetic polymorphisms, renal impairment, cirrhosis, and/or inflammation. Current knowledge on the impact of each of these factors on drug exposure and DDIs is summarized and future perspectives for the management of such complex DDIs in clinical practice are discussed, including the use of advanced Computerized Physician Order Entry (CPOE) systems, the development of model-based dose optimization strategies, and the education of healthcare professionals with respect to personalized medicine.

Pharmacogenetics of drug-drug interaction and drug-drug-gene interaction: a systematic review on CYP2C9, CYP2C19 and CYP2D6

Currently, most guidelines on drug-drug interaction (DDI) neither consider the potential effect of genetic polymorphism in the strength of the interaction nor do they account for the complex interaction caused by the combination of DDI and drug-gene interaction (DGI) where there are multiple biotransformation pathways, which is referred to as drug-drug-gene interaction (DDGI). In this systematic review, we report the impact of pharmacogenetics on DDI and DDGI in which three major drug-metabolizing enzymes - CYP2C9, CYP2C19 and CYP2D6 - are central. We observed that several DDI and DDGI are highly gene-dependent, leading to a different magnitude of interaction. Precision drug therapy should take pharmacogenetics into account when drug interactions in clinical practice are expected.

One size fits one: pharmacogenetics in gastroenterology

Individual variability in response and development of adverse effects to drugs is a major challenge in clinical practice. Pharmacogenomics refers to the aspect of personalized medicine where the patient's genetic information instructs the selection and dosage of therapy while also predicting its adverse effects profile. Sequencing of the entire human genome has given us the opportunity to study commonly used drugs as well as newer therapeutic agents in a new light, opening up opportunities for better drug efficacy and decreased adverse effects. This article highlights developments in pharmacogenomics, relates these to practice of gastroenterology, and outlines roadblocks in translation of this knowledge into clinical practice.