Pomegranate-containing products and tacrolimus: A potential interaction

Impact of Pomegranate Juice on the Pharmacokinetics of CYP3A4- and CYP2C9-Mediated Drugs Metabolism: A Preclinical and Clinical Review

The Punica granatum L. (pomegranate) fruit juice contains large amounts of polyphenols, mainly tannins such as ellagitannin, punicalagin, and punicalin, and flavonoids such as anthocyanins, flavan-3-ols, and flavonols. These constituents have high antioxidant, anti-inflammatory, anti-diabetic, anti-obesity, and anticancer activities. Because of these activities, many patients may consume pomegranate juice (PJ) with or without their doctor's knowledge. This may raise any significant medication errors or benefits because of food-drug interactions that modulate the drug's pharmacokinetics or pharmacodynamics. It has been shown that some drugs exhibited no interaction with pomegranate, such as theophylline. On the other hand, observational studies reported that PJ prolonged the pharmacodynamics of warfarin and sildenafil. Furthermore, since it has been shown that pomegranate constituents inhibit cytochrome P450 (CYP450) activities such as CYP3A4 and CYP2C9, PJ may affect intestinal and liver metabolism of CYP3A4 and CYP2C9-mediated drugs. This review summarizes the preclinical and clinical studies that investigated the impact of oral PJ administration on the pharmacokinetics of drugs that are metabolized by CYP3A4 and CYP2C9. Thus, it will serve as a future road map for researchers and policymakers in the fields of drug-herb, drug-food and drug-beverage interactions. Preclinical studies revealed that prolonged administration of PJ increased the absorption, and therefore the bioavailability, of buspirone, nitrendipine, metronidazole, saquinavir, and sildenafil via reducing the intestinal CYP3A4 and CYP2C9. On the other hand, clinical studies are limited to a single dose of PJ administration that needs to be protocoled with prolonged administration to observe a significant interaction.

Potential profound fluctuation in tacrolimus concentration on consumption of pomegranate rind extract: A Pharmacokinetic Experiment

Background: Presently, varied case reports demonstrated an increase or decrease in blood concentration of diverse conventional drugs, often co-administered with edible fruits, spices, or vegetables. The overarching aim of this research is to elucidate the fluctuations in tacrolimus (TAC) blood concentration on the consumption of pomegranate rind extract (PRE). Methods: A pharmacokinetic (PK) study was conducted with two groups, vis-a-vis PRE + TAC (3 mg/kg) and TAC (3 mg/kg) alone groups. An experimental study was conducted in three different manners: Single-dose (S) PRE (200 mg/kg), 7-day repetitive (7-R) PRE (200 mg/kg) dosing, and multiple (M) PRE doses (100, 200, 400, and 800 mg/kg). All the blood samples (approximately 300 μl) were drawn at different time intervals, i.e., 30 min, 1, 2, 4, 8, and 12 h after oral administration of TAC (3 mg/kg). The estimation of TAC in rat plasma was done using the hyphenated technique LC-MS/MS where the mass spectrometer used was a triple-stage quadrupole in multiple-reaction monitoring (MRM) mode. Results: The findings depict that in comparison with the TAC (3 mg/kg) alone group with the 7-day repetitive (7-R) PRE (200 mg/kg) dosing, the Cmax was found to be 9.03 ± 1.21 ng/ml; AUC from time zero to infinity (AUC0-∞), 61.91 ± 17.37 ngh/ml, while the TAC (3 mg/kg) + PRE group exhibited an increase in PK parameters of TAC (Cmax 22.48 ± 3.07 ng/ml; AUC0-∞ 153.08 ± 13.24 ng h/ml). The authors further investigated in what manner the PRE affects the PK of TAC in animals. For this, docking studies with major phytoconstituents present in the PRE with CYP3A4 isoenzyme were carried out. Ellagitannins (dock score, -11.64) and punicalagin (dock score, -10.68) were again used for molecular simulation studies with TAC. To validate our findings, a CYP3A4 inhibitory in vitro assay was conducted. Conclusion: Based on the integrated in vivo and in silico studies, we concluded that pomegranate rind extract interacts strongly with CYP isoenzyme and is therefore responsible for the altered PK profile of TAC.

Post-transplant education for kidney recipients and their caregivers

Successful outcomes in pediatric kidney transplantation require the involvement of the transplant team as well as recipients and their caregivers. Enhancing patient and family understanding of the disease and of post-transplant care can result in improved adherence and outcomes. Educational strategies should aim to be broad, understandable, innovative, and inclusive while maintaining a tailored approach to individualized care. Teaching should not be viewed as a one-time event but rather as an ongoing conversation throughout the duration of care, emphasizing different aspects throughout the patient's various developmental stages. The following review article discusses the content and methods of post-transplant education.

Controversial Interactions of Tacrolimus with Dietary Supplements, Herbs and Food

Tacrolimus is an immunosuppressive calcineurin inhibitor used to prevent rejection in allogeneic organ transplant recipients, such as kidney, liver, heart or lung. It is metabolized in the liver, involving the cytochrome P450 (CYP3A4) isoform CYP3A4, and is characterized by a narrow therapeutic window, dose-dependent toxicity and high inter-individual and intra-individual variability. In view of the abovementioned facts, the aim of the study is to present selected interactions between tacrolimus and the commonly used dietary supplements, herbs and food. The review was based on the available scientific literature found in the PubMed, Scopus and Cochrane databases. An increase in the serum concentration of tacrolimus can be caused by CYP3A4 inhibitors, such as grapefruit, pomelo, clementine, pomegranate, ginger and turmeric, revealing the side effects of this drug, particularly nephrotoxicity. In contrast, CYP3A4 inducers, such as St. John’s Wort, may result in a lack of therapeutic effect by reducing the drug concentration. Additionally, the use of Panax ginseng, green tea, Schisandra sphenanthera and melatonin in patients receiving tacrolimus is highly controversial. Therefore, since alternative medicine constitutes an attractive treatment option for patients, modern healthcare should emphasize the potential interactions between herbal medicines and synthetic drugs. In fact, each drug or herbal supplement should be reported by the patient to the physician (concordance) if it is taken in the course of immunosuppressive therapy, since it may affect the pharmacokinetic and pharmacodynamic parameters of other preparations.

Predictors of tacrolimus pharmacokinetic variability: current evidences and future perspectives

INTRODUCTION

In kidney transplantation, tacrolimus (TAC) is at the cornerstone of current immunosuppressive strategies. Though because of its narrow therapeutic index, it is critical to ensure that TAC levels are maintained within this sharp window through reactive adjustments. This would allow maximizing efficiency while limiting drug-associated toxicity. However, TAC high intra- and inter-patient pharmacokinetic (PK) variability makes it more laborious to accurately predict the appropriate dosage required for a given patient.

AREAS COVERED

This review summarizes the state-of-the-art knowledge regarding drug interactions, demographic and pharmacogenetics factors as predictors of TAC PK. We provide a scoring index for each association to grade its relevance and we present practical recommendations, when possible for clinical practice.

EXPERT OPINION

The management of TAC concentration in transplanted kidney patients is as critical as it is challenging. Recommendations based on rigorous scientific evidences are lacking as knowledge of potential predictors remains limited outside of DDIs. Awareness of these limitations should pave the way for studies looking at demographic and pharmacogenetic factors as well as gut microbiota composition in order to promote tailored treatment plans. Therapeutic approaches considering patients' clinical singularities may help allowing to maintain appropriate concentration of TAC.

Pomegranate Juice does not Affect the Bioavailability of Cyclosporine in Healthy Thai Volunteers

Background

It is still controversial whether pomegranate causes drug interactions. Pomegranate juice has been shown to inhibit CYP3A in-vitro and animal studies. The co-administration of pomegranate juice with cyclosporine, a narrow therapeutic drug that is the substrate of CYP3A, might lead to drug toxicity. The objective of this study is to investigate the effect of pomegranate juice on the pharmacokinetics of cyclosporine in healthy Thai volunteers.

Methods

The study design was an open-label, randomized, single dose, crossover study with a 2-week washout period. Each fasting subject received 2 microemulsion tablets of 100 mg of cyclosporine with 500 ml of pomegranate juice (test) or 500 ml of water (control). Serial blood samples were collected up to 24 h after dosing, and blood samples were analyzed for cyclosporine concentrations by using chemiluminescent microparticle immunoassay. Fourteen healthy volunteers completed the study.

Results

The 90% confidence intervals for the test/control ratio using logarithmically transformed data of area under the concentration-time curve (AUC) from time zero until the last measured concentration (AUC0-t), AUC from time zero to infinity (AUC0-∞), and maximum concentration (Cmax) were 91.6-105.6, 92.0-105.2 and 82.3-102.5, respectively. The results were within the accepted bioequivalence range for narrow therapeutic index drugs (90-111% for AUC and 80-125% for Cmax). There were no differences in adverse event between the groups.

Conclusion

Single dose administration of pomegranate juice with cyclosporine did not significantly affect the oral bioavailability of cyclosporine. However, further work is needed to thoroughly evaluate the effect of pomegranate on narrow therapeutic drugs.

Efficacy and safety of pomegranate medicinal products for cancer

Preclinical in vitro and in vivo studies demonstrate potent effects of pomegranate preparations in cancer cell lines and animal models with chemically induced cancers. We have carried out one systematic review of the effectiveness of pomegranate products in the treatment of cancer and another on their safety. The PubMed search provided 162 references for pomegranate and cancer and 122 references for pomegranate and safety/toxicity. We identified 4 clinical studies investigating 3 pomegranate products, of which one was inappropriate because of the low polyphenol content. The evidence of clinical effectiveness was poor because the quality of the studies was poor. Although there is no concern over safety with the doses used in the clinical studies, pomegranate preparations may be harmful by inducing synthetic drug metabolism through activation of liver enzymes. We have analysed various pomegranate products for their content of anthocyanins, punicalagin, and ellagic acid in order to compare them with the benchmark doses from published data. If the amount of coactive constituents is not declared, patients risk not benefiting from the putative pomegranate effects. Moreover, pomegranate end products are affected by many determinants. Their declaration should be incorporated into the regulatory guidance and controlled before pomegranate products enter the market.

Pomegranate juice does not affect the disposition of simvastatin in healthy subjects

Previous in vitro and in vivo investigations reported controversial results for the inhibitory potential of pomegranate on Cytochrome P450 (CYP) 3A activity. This study evaluated the effect of pomegranate juice on the disposition of simvastatin, a CYP3A4 substrate, and simvastatin acid, its active metabolite, compared with grapefruit juice in healthy subjects. A single oral pharmacokinetic study of 40 mg simvastatin was conducted as a three-way crossover (control, pomegranate, and grapefruit juices) in 12 healthy male subjects. The subjects took pomegranate or grapefruit juice three times per day for 3 days (900 mL/day) and on the third day, the pharmacokinetic study was executed. Blood samples were collected to 24 h post-dose and the pharmacokinetic parameters of simvastatin and simvastatin acid were compared among the study periods. In the period of grapefruit juice, the mean C max and AUCinf of simvastatin [the geometric mean ratio (90 % CI) 15.6 (11.6-21.0) and 9.1 (6.0-13.7)] were increased significantly when compared with the control period, whereas they were not significantly different in the period of pomegranate juice [C max and AUCinf 1.20 (0.89-1.62) and 1.29 (0.85-1.94)]. The mean C max and AUCinf of simvastatin acid were increased significantly after intake of grapefruit juice, but not pomegranate juice. These results suggest that pomegranate juice affects little on the disposition of simvastatin in humans. Pomegranate juice does not seem to have a clinically relevant inhibitory potential on CYP3A4 activity.