CYP2C19 Gene Profiling as a Tool for Personalized Stress Ulcer Prophylaxis With Proton Pump Inhibitors in Critically Ill Patients - Recommendations Proposal.

To this date, there are no recommendations for personalized stress ulcer prophylaxis (SUP) in critical care that would take the patient's individual genetic predispositions into account. Of drugs used for this purpose, proton pump inhibitors (PPIs) are the first-choice drugs in intensive care unit patients. The degradation of proton pump inhibitors is mediated by cytochrome P450 (CYP) enzymes; in particular, CYP2C19 and, to a lesser extent, CYP3A4 are involved. Expression and metabolic activity of, namely in, CYP2C19 is significantly affected by single nucleotide polymorphisms, the drug metabolization rate varies greatly from ultrarapid to poor and likely influences the optimal dosage. As these CYP2C19 predictive phenotypes via CYP2C19 haplogenotypes (rs12248560/rs4244285) can be relatively easily determined using the current standard equipment of hospital laboratories, we prepared a set of recommendations for personalized PPI-based stress ulcer prophylaxis taking into account the patient's CYP2C19 predictive phenotype determined in this way. These recommendations are valid, in particular, for European, American and African populations, because these populations have the high representations of the CYP2C19*17 allele associated with the overexpression of the CYP2C19 gene and ultrarapid degradation of PPIs. We propose the CYP2C19 gene profiling as a tool for personalized SUP with PPI in critically ill patients.

Lycopene increases metabolic activity of rat liver CYP2B, CYP2D and CYP3A.

BACKGROUND: Lycopene as a naturally occurring carotenoid is a common part of the human diet. Several beneficial properties of lycopene have been identified, with the most studied being anti-cancer and antioxidant activity. However, no evidence of possible drug-drug or drug-food supplement interactions has been found. METHODS: We studied the in vivo effect of lycopene on the selected rat liver cytochromes P450 (CYPs): CYP1A2, CYP2B, CYP2C11, CYP2C6, CYP2D, and CYP3A. Lycopene was administered to rats intragastrically at doses of 4, 20, and 100 mg/kg/day for 10 consecutive days. Total protein content, P450 Content, and metabolic activity of selected CYPs were evaluated in the rat liver microsomal fraction. RESULTS: Increased CYP2B, CYP2D, and CYP3A metabolic activities were observed in animals treated with the lycopene dose of 100 mg/kg/day. The content of CYP3A1 protein was increased by the dose of 100 mg/kg/day and CYP3A2 protein was increased by all administered doses of lycopene. CONCLUSION: The results of our study indicate that lycopene increased the metabolic activity of enzymes that are orthologues to the most clinically important human enzymes involved in xenobiotic metabolism. The risk of pharmacokinetic interactions between lycopene dietary supplements and co-administered drugs should be evaluated.

Effect of Endocannabinoid Oleamide on Rat and Human Liver Cytochrome P450 Enzymes in In Vitro and In Vivo Models.

The endocannabinoid system is important for many physiologic and pathologic processes, but its role in the regulation of liver cytochromes P450 (P450s) remains unknown. We studied the influence of the endocannabinoid oleamide on rat and human liver P450s. Oleamide was administered intraperitoneally to rats at doses of 0.1, 1, and 10 mg/kg per day for 7 days. The content and activity of key P450s were evaluated in rat liver microsomes. Moreover, interactions with nuclear receptors regulating P450 genes and serum levels of their ligands (prolactin, corticosterone, and free triiodothyronine) were tested in in vitro P450 inhibition assays. Decreased protein levels and metabolic activities of CYP1A2, CYP2B, and CYP2C11, along with a drop in metabolic activity of CYP2D2, were observed in animals treated with oleamide (10 mg/kg per day). The activities of CYP2C6, CYP2A, and CYP3A and the levels of hormones were not altered. In vitro, oleamide exhibited a weak inhibition of rat CYP1A2, CYP2D2, and CYP2C6. The activities of rat CYP2A, CYP2B, CYP2C11, and CYP3A and human CYP1A2, CYP2B6, CYP2C9, and CYP3A4 were not altered. Oleamide did not interact with human pregnane X, constitutive androstane, or aryl hydrocarbon receptors in reporter gene experiments and did not regulate their target P450 genes in primary human hepatocytes. Our results indicate that oleamide caused the downregulation of some rat liver P450s, and hormones are not mediators of this effect. In vitro oleamide inhibits mainly rat CYP2C6 and is neither an agonist nor antagonist of major human nuclear receptors involved in the regulation of xenobiotic metabolism.

Cannabinoids and Cytochrome P450 Interactions.

OBJECTIVE: This review consists of three parts, representing three different possibilities of interactions between cannabinoid receptor ligands of both exogenous and endogenous origin and cytochrome P450 enzymes (CYPs). The first part deals with cannabinoids as CYP substrates, the second summarizes current knowledge on the influence of various cannabinoids on the metabolic activity of CYP, and the third outline a possible involvement of the endocannabinoid system and cannabinoid ligands in the regulation of CYP liver activity. METHODS: We performed a structured search of bibliographic and drug databases for peer-reviewed literature using focused review questions. RESULTS: Biotransformation via a hydrolytic pathway is the major route of endocannabinoid metabolism and the deactivation of substrates is characteristic, in contrast to the minor oxidative pathway via CYP involved in the bioactivation reactions. Phytocannabinoids are extensively metabolized by CYPs. The enzymes CYP2C9, CYP2C19, and CYP3A4 catalyze most of their hydroxylations. Similarly, CYP represents a major metabolic pathway for both synthetic cannabinoids used therapeutically and drugs that are abused. In vitro experiments document the mostly CYP inhibitory activity of the major phytocannabinoids, with cannabidiol as the most potent inhibitor of many CYPs. The drug-drug interactions between cannabinoids and various drugs at the CYP level are reported, but their clinical relevance remains unclear. The direct activation/inhibition of nuclear receptors in the liver cells by cannabinoids may result in a change of CYP expression and activity. Finally, we hypothesize the interplay of central cannabinoid receptors with numerous nervous systems, resulting in a hormone-mediated signal towards nuclear receptors in hepatocytes.

Effects of combined treatment with cognitive enhancer memantine and antidepressant fluoxetine on CYP2D2 metabolic activity in rats.

OBJECTIVES: The drug-drug interactions can result in alterations of the therapeutical responses. The present study was designed to investigate possible pharmacokinetic interactions between the cognitive agent memantine and the antidepressant fluoxetine combined often in treatments of cognitive disorders including Alzheimer disease. The attention was focused on changes of the cytochrome P450 2D2 isoenzyme activity in two animal models. METHODS AND DESIGN: The tested drugs were administered alone or in a combination to rat males and their effects on the 2D2 isoenzyme activity was determined after in vivo administration. The levels of marker dextromethorphan, its 2D2 specific metabolite dextrorphan were analyzed in plasma of rats and using the model of isolated perfused rat liver in the perfusion medium. The dextromethorphan/dextrorphan (DEM/DEX) metabolic ratios were determined as a sign of inhibitory influences on CYP2D2. RESULTS: The analyses showed elevation of DEM/DEX metabolic ratio after all treatments: a) memantine, b) fluoxetine and c) memantine+fluoxetine, however the results were not completely identical. The intensity of inhibitory effects on the CYP2D2 activity were: memantine < memantine + fluoxetine < fluoxetine. CONCLUSION: The results presented suggest that the clinical pharmacotherapeutical approach to combine memantine with fluoxetine is from the point of view of pharmacokinetic drug-drug interaction on the level of CYP2D2 isoenzyme safe and even of benefit as memantine could elicit a suppression of the inhibitory influence of fluoxetine.

Intersexual differences in inhibitory influence of trans-resveratrol on activity of cytochrome P450 2D2 in rats.

OBJECTIVES: Differences in the metabolism between males and females have been seen over time. Hormonal regulation of cytochrome P450 activity is understood to be involved. Trans-resveratrol (RES) is an estrogenically active plant polyphenol with many protective biological activities including neuroprotection. The present report studied the influence of sex and RES on variances in rat's cytochrome P450 2D2 hepatic metabolic activity. METHODS AND DESIGN: Isolated perfused rat liver was used for determination of cytochrome P450 2D2 activity. Wistar albino rats of both sexes were treated with RES at the dose of 5 mg/kg/day for 10 days prior to liver isolation. Levels of marker substance dextromethorphan (DEM) and its 2D2 specific metabolite dextrorphan (DEX) were measured during perfusion. The metabolic ratios (DEM/DEX) and the levels of DEM and DEX in perfusate were compared. RESULTS: In the controls, the activity of CYP2D2 was found to be higher in male rats compared to females. RES produced inhibition of CYP2D2, expressed by significant changes of both DEM and DEX levels in males and significant increase of only DEM levels in females. There were no gender changes in DEX levels in RES treated animals whilst DEM levels were significantly increased during the whole perfusion in females. CONCLUSION: The results confirmed gender differences in the metabolic activity of CYP450 2D2 with a higher rate in male rats. RES acted as an inhibitor, however again with greater impact in males than in females. This metabolic divergence could be a cause for different sensitivity or even toxicity of drugs metabolized by the CYP450 2D2.