Roles of diclofenac and its metabolites in immune activation associated with acute hepatotoxicity in TgCYP3A4/hPXR-humanized mice

Fasting potentiates diclofenac-induced liver injury via inductions of oxidative/endoplasmic reticulum stresses and apoptosis, and inhibition of autophagy by depleting hepatic glutathione in mice

Diclofenac, a widely used non-steroidal anti-inflammatory drug, can cause liver damage via its metabolic activation by hepatic CYP450s and UGT2B7. Fasting can affect drug-induced liver injury by modulating the hepatic metabolism, but its influence on diclofenac hepatotoxicity is unknown. Thus, we investigated diclofenac-induced liver damage after fasting in mice, and the cellular events were examined. Male ICR mice fasted for 16 h showed the elevation of CYP3A11, but the decreases of UGT2B7, glutathione (GSH), and GSH S-transferase-μ/-π levels in the livers. Diclofenac (200 mg/kg) injection into the mice after 16-h fasting caused more significant liver damage compared to that in the diclofenac-treated fed mice, as shown by the higher serum ALT and AST activities. Diclofenac-promoted hepatic oxidative stress (oxidized proteins, 4-hydroxynonenal, and malondialdehyde), endoplasmic reticulum (ER) stress (BiP, ATF6, and CHOP), and apoptosis (cleaved caspase-3 and cleaved PARP) were enhanced by fasting. Autophagic degradation was inhibited in the diclofenac-treated fasting mice compared to that of the corresponding fed mice. The results suggest that fasting can make the liver more susceptible to diclofenac toxicity by lowering GSH-mediated detoxification; increased oxidative/ER stresses and apoptosis and suppressed autophagic degradation may be the cellular mechanisms of the aggravated diclofenac hepatotoxicity under fasting conditions.

Nanoencapsulated Curcumin Mitigates Liver Injury and Drug-Metabolizing Enzymes Induction in Diclofenac-Treated Mice

Curcumin (CUR) is a natural product with known anti-inflammatory, antioxidant, and hepatoprotective properties. The aim of this study was to formulate CUR into a polymeric nanoparticle (NP) formulation and examine its potential hepatoprotective activity in an animal model of diclofenac (DIC)-induced hepatotoxicity. CUR was loaded into polymeric NPs composed of poly(ethylene glycol)-polycaprolactone (PEG-PCL). The optimal CUR NPs were evaluated against DIC-induced hepatotoxicity in mice, by studying the histopathological changes and gene expression of drug-metabolizing cyp450 (cyp2c29 and cyp2d9) and ugt (ugt2b1) genes in the livers of the animals. The optimal NPs were around 67 nm in diameter with more than 80% loading efficiency and sustained release. Histological findings of mice livers revealed that CUR NPs exhibited a superior hepatoprotective effect compared to free CUR, and both groups reduced DIC-mediated liver tissue injury. While treatment with DIC alone or with CUR and CUR NPs had no effect on cyp2c29 gene expression, cyp2d9 and ugt2b1 genes were upregulated in the DIC-treated group, and this effect was reversed by CUR both as a free drug and as CUR NPs. Our findings present a promising application for nanoencapsulated CUR in the treatment of nonsteroidal anti-inflammatory drugs-induced liver injury and the associated dysregulation in the expression of hepatic drug-metabolizing enzymes.

Drug-induced liver injury and anti-hepatotoxic effect of herbal compounds: a metabolic mechanism perspective

BACKGROUND

Drug-induced liver injury (DILI) is the most challenging and thought-provoking liver problem for hepatologists owing to unregulated medication usage in medical practices, nutritional supplements, and botanicals. Due to underreporting, analysis, and identification issues, clinically evaluated medication hepatotoxicity is prevalent yet hard to quantify.

PURPOSE

This review's primary objective is to thoroughly compare pharmaceutical drugs and herbal compounds that have undergone clinical trials, focusing on their metabolic mechanisms contributing to the onset of liver illnesses and their hepatoprotective effects.

METHODS

The data was gathered from several online sources, such as PubMed, Scopus, Google Scholar, and Web of Science, using appropriate keywords.

RESULTS

The prevalence of conventional and herbal medicine is rising. A comprehensive understanding of the metabolic mechanism is necessary to mitigate the hepatotoxicity induced by drugs and facilitate the incorporation or substitution of herbal medicine instead of pharmaceuticals. Moreover, pre-clinical pharmacological research has the potential to facilitate the development of natural products as therapeutic agents, displaying promising possibilities for their eventual clinical implementation.

CONCLUSIONS

Acetaminophen, isoniazid, rifampicin, diclofenac, and pyrogallol have been identified as the most often reported synthetic drugs that produce hepatotoxicity by oxidative stress, inflammation, apoptosis, and fibrosis during the last several decades. Due to their ability to downregulate many factors (such as cytokines) and activate several enzyme/enzyme systems, herbal substances (such as Gingko biloba extract, curcumin, resveratrol, and silymarin) provide superior protection against harmful mechanisms which induce hepatotoxicity with fewer adverse effects than their synthetic counterparts.

The molecular pathogenesis of triptolide-induced hepatotoxicity

Triptolide (TP) is the major pharmacologically active ingredient and toxic component of Tripterygium wilfordii Hook. f. However, its clinical potential is limited by a narrow therapeutic window and multiple organ toxicity, especially hepatotoxicity. Furthermore, TP-induced hepatotoxicity shows significant inter-individual variability. Over the past few decades, research has been devoted to the study of TP-induced hepatotoxicity and its mechanism. In this review, we summarized the mechanism of TP-induced hepatotoxicity. Studies have demonstrated that TP-induced hepatotoxicity is associated with CYP450s, P-glycoprotein (P-gp), oxidative stress, excessive autophagy, apoptosis, metabolic disorders, immunity, and the gut microbiota. These new findings provide a comprehensive understanding of TP-induced hepatotoxicity and detoxification.

Preclinical models of idiosyncratic drug-induced liver injury (iDILI): Moving towards prediction

Idiosyncratic drug-induced liver injury (iDILI) encompasses the unexpected harms that prescription and non-prescription drugs, herbal and dietary supplements can cause to the liver. iDILI remains a major public health problem and a major cause of drug attrition. Given the lack of biomarkers for iDILI prediction, diagnosis and prognosis, searching new models to predict and study mechanisms of iDILI is necessary. One of the major limitations of iDILI preclinical assessment has been the lack of correlation between the markers of hepatotoxicity in animal toxicological studies and clinically significant iDILI. Thus, major advances in the understanding of iDILI susceptibility and pathogenesis have come from the study of well-phenotyped iDILI patients. However, there are many gaps for explaining all the complexity of iDILI susceptibility and mechanisms. Therefore, there is a need to optimize preclinical human in vitro models to reduce the risk of iDILI during drug development. Here, the current experimental models and the future directions in iDILI modelling are thoroughly discussed, focusing on the human cellular models available to study the pathophysiological mechanisms of the disease and the most used in vivo animal iDILI models. We also comment about in silico approaches and the increasing relevance of patient-derived cellular models.

Amelioration of the hepatotoxic effects of nonsteroidal drugs using vitamin C and determination of their relationship with the lipid profile

Objective

Despite the various clinical benefits of nonsteroidal anti-inflammatory drugs, their frequent and prolonged use has led to numerous health risks, including hepatotoxicity. Hepatotoxicity mediated by oxidative stress can affect the lipid profile. The objective was to investigate whether post-treatment with vitamin C can ameliorate the effects of diclofenac and naproxen in the livers of prepubertal rats and to highlight their relationship with lipid profile.

Methods

Forty prepubertal female albino rats were distributed among the control group, the diclofenac-administered group (5 mg/kg/day), and the naproxen-administered group (50 mg/kg/day). This study included two phases. In Phase 1, only five rats from each group were dissected after 21 days of oral administration to assess the hepatotoxic effects of nonsteroidal drugs. In Phase 2, five of the remaining animals in each intervention group were post-treated with 25 mg/kg/day of vitamin C for an additional 21 days. After the administration and post-treatment, serum biochemical parameters and histopathological signs were evaluated.

Results

Extreme elevation in the levels of aspartate and alanine aminotransferases was observed in the diclofenac and naproxen groups compared with those in the control (p < 0.001). In addition, the levels of high- and low-density lipoproteins were significantly impacted in these drug groups (p < 0.01, p < 0.05 respectively). Several pathological signs in the liver histology were observed in both drug groups. After post-treatment with vitamin C, noticeable amelioration of these alterations was observed. There were slightly elevation in the liver enzymes and insignificant increase and decrease in the high and low-density lipoproteins respectively.

Conclusion

Vitamin C post-treatment ameliorated the hepatotoxicity induced by diclofenac sodium and naproxen.

Recent developments in in vitro and in vivo models for improved translation of preclinical pharmacokinetics and pharmacodynamics data

Improved pharmacokinetics/pharmacodynamics (PK/PD) prediction in the early stages of drug development is essential to inform lead optimization strategies and reduce attrition rates. Recently, there have been significant advancements in the development of new in vitro and in vivo strategies to better characterize pharmacokinetic properties and efficacy of drug leads. Herein, we review advances in experimental and mathematical models for clearance predictions, advancements in developing novel tools to capture slowly metabolized drugs, in vivo model developments to capture human etiology for supporting drug development, limitations and gaps in these efforts, and a perspective on the future in the field.