Ursodeoxycholic acid (UDCA) prevents DCA effects on male mouse liver via up-regulation of CYP [correction of CXP] and preservation of BSEP activities

Induction of hepatic CYP3A4 expression by cholesterol and cholic acid: Alterations of gene expression, microsomal activity, and pharmacokinetics

Human cytochrome P450 3A4 (CYP3A4) is a drug-metabolizing enzyme that is abundantly expressed in the liver and intestine. It is an important issue whether compounds of interest affect the expression of CYP3A4 because more than 30% of commercially available drugs are metabolized by CYP3A4. In this study, we examined the effects of cholesterol and cholic acid on the expression level and activity of CYP3A4 in hCYP3A mice that have a human CYP3A gene cluster and show human-like regulation of the coding genes. A normal diet (ND, CE-2), CE-2 with 1% cholesterol and 0.5% cholic acid (HCD) or CE-2 with 0.5% cholic acid was given to the mice. The plasma concentrations of cholesterol, cholic acid and its metabolites in HCD mice were higher than those in ND mice. In this condition, the expression levels of hepatic CYP3A4 and the hydroxylation activities of triazolam, a typical CYP3A4 substrate, in liver microsomes of HCD mice were higher than those in liver microsomes of ND mice. Furthermore, plasma concentrations of triazolam in HCD mice were lower than those in ND mice. In conclusion, our study suggested that hepatic CYP3A4 expression and activity are influenced by the combination of cholesterol and cholic acid in vivo.

Sox9EGFP Defines Biliary Epithelial Heterogeneity Downstream of Yap Activity

BACKGROUND & AIMS

Defining the genetic heterogeneity of intrahepatic biliary epithelial cells (BECs) is challenging, and tools for identifying BEC subpopulations are limited. Here, we characterize the expression of a Sox9^EGFP transgene in the liver and demonstrate that green fluorescent protein (GFP) expression levels are associated with distinct cell types.

METHODS

Sox9^EGFP BAC transgenic mice were assayed by immunofluorescence, flow cytometry, and gene expression profiling to characterize in vivo characteristics of GFP populations. Single BECs from distinct GFP populations were isolated by fluorescence-activated cell sorting, and functional analysis was conducted in organoid forming assays. Intrahepatic ductal epithelium was grown as organoids and treated with a Yes-associated protein (Yap) inhibitor or bile acids to determine upstream regulation of Sox9 in BECs. Sox9^EGFP mice were subjected to bile duct ligation, and GFP expression was assessed by immunofluorescence.

RESULTS

BECs express low or high levels of GFP, whereas periportal hepatocytes express sublow GFP. Sox9^EGFP+ BECs are differentially distributed by duct size and demonstrate distinct gene expression signatures, with enrichment of Cyr61 and Hes1 in GFP^high BECs. Single Sox9^EGFP+ cells form organoids that exhibit heterogeneous survival, growth, and HNF4A activation dependent on culture conditions, suggesting that exogenous signaling impacts BEC heterogeneity. Yap is required to maintain Sox9 expression in biliary organoids, but bile acids are insufficient to induce BEC Yap activity or Sox9 in vivo and in vitro. Sox9^EGFP remains restricted to BECs and periportal hepatocytes after bile duct ligation.

CONCLUSIONS

Our data demonstrate that Sox9^EGFP levels provide readout of Yap activity and delineate BEC heterogeneity, providing a tool for assaying subpopulation-specific cellular function in the liver.

Single-Cell Analysis of the Liver Epithelium Reveals Dynamic Heterogeneity and an Essential Role for YAP in Homeostasis and Regeneration

The liver can substantially regenerate after injury, with both main epithelial cell types, hepatocytes and biliary epithelial cells (BECs), playing important roles in parenchymal regeneration. Beyond metabolic functions, BECs exhibit substantial plasticity and in some contexts can drive hepatic repopulation. Here, we performed single-cell RNA sequencing to examine BEC and hepatocyte heterogeneity during homeostasis and after injury. Instead of evidence for a transcriptionally defined progenitor-like BEC cell, we found significant homeostatic BEC heterogeneity that reflects fluctuating activation of a YAP-dependent program. This transcriptional signature defines a dynamic cellular state during homeostasis and is highly responsive to injury. YAP signaling is induced by physiological bile acids (BAs), required for BEC survival in response to BA exposure, and is necessary for hepatocyte reprogramming into biliary progenitors upon injury. Together, these findings uncover molecular heterogeneity within the ductal epithelium and reveal YAP as a protective rheostat and regenerative regulator in the mammalian liver.

Altered bile acid profile associates with cognitive impairment in Alzheimer's disease-An emerging role for gut microbiome

INTRODUCTION

Increasing evidence suggests a role for the gut microbiome in central nervous system disorders and a specific role for the gut-brain axis in neurodegeneration. Bile acids (BAs), products of cholesterol metabolism and clearance, are produced in the liver and are further metabolized by gut bacteria. They have major regulatory and signaling functions and seem dysregulated in Alzheimer's disease (AD).

METHODS

Serum levels of 15 primary and secondary BAs and their conjugated forms were measured in 1464 subjects including 370 cognitively normal older adults, 284 with early mild cognitive impairment, 505 with late mild cognitive impairment, and 305 AD cases enrolled in the AD Neuroimaging Initiative. We assessed associations of BA profiles including selected ratios with diagnosis, cognition, and AD-related genetic variants, adjusting for confounders and multiple testing.

RESULTS

In AD compared to cognitively normal older adults, we observed significantly lower serum concentrations of a primary BA (cholic acid [CA]) and increased levels of the bacterially produced, secondary BA, deoxycholic acid, and its glycine and taurine conjugated forms. An increased ratio of deoxycholic acid:CA, which reflects 7α-dehydroxylation of CA by gut bacteria, strongly associated with cognitive decline, a finding replicated in serum and brain samples in the Rush Religious Orders and Memory and Aging Project. Several genetic variants in immune response-related genes implicated in AD showed associations with BA profiles.

DISCUSSION

We report for the first time an association between altered BA profile, genetic variants implicated in AD, and cognitive changes in disease using a large multicenter study. These findings warrant further investigation of gut dysbiosis and possible role of gut-liver-brain axis in the pathogenesis of AD.

Different effects of ursodeoxycholic acid on intrahepatic cholestasis in acute and recovery stages induced by alpha-naphthylisothiocyanate in mice

The aim of this study was to determine the effect of ursodeoxycholic acid (UDCA) on the alpha-naphthylisothiocyanate (ANIT)-induced acute and recovery stage of cholestasis model mice. In the acute stage of model mice, pretreatment with UDCA (25, 50, and 100 mg·kg^-1, ig) for 12 days prior to ANIT administration (50 mg·kg^-1, ig) resulted in the dramatic increase in serum biochemistry, with aggrevation of bile infarcts and hepatocyte necrosis. The elevation of beta-muricholic acid (β-MCA), cholic acid (CA), and taurocholic acid (TCA) in serum and liver, and reduction of these bile acids (BAs) in bile was observed. In contrast, in the recovery stage of model mice, treatment with UDCA (25, 50, and 100 mg·kg^-1, ig) for 7 days after ANIT administration (50 mg·kg^-1, ig) resulted in the significant decrease in levels of serum alanine aminotransferase (ALT) and total bile acid (TBA). Liver injury was attenuated, and the levels of TBA, CA, TCA, and β-MCA in the liver were significantly decreased. Additionally, UDCA can upregulate expression of BSEP, but it cannot upregulate expression of AE2. UDCA, which induced BSEP to increase bile acid-dependent bile flow, aggravated cholestasis and liver injury when the bile duct was obstructed in the acute stage of injury in model mice. In contrast, UDCA alleviated cholestasis and liver injury induced by ANIT when the obstruction was improved in the recovery stage.

U12, a UDCA derivative, acts as an anti-hepatoma drug lead and inhibits the mTOR/S6K1 and cyclin/CDK complex pathways

U12, one of 20 derivatives synthesized from ursodeoxycholic acid (UDCA), has been found to have anticancer effects in liver cancer cell lines (SMMC-7721 and HepG2) and to protect normal liver cells from deoxycholic acid (DCA) damage (QSG-7701). Its anticancer mechanism was investigated using computer-aided network pharmacology and comparative proteomics. Results showed that its anti-malignancy activities were activated by mTOR/S6K1, cyclinD1/CDK2/4 and caspase-dependent apoptotic signaling pathways in hepatocellular carcinoma cells (HCC). The action of U12 may be similar to that of rapamycin. Animal testing confirmed that U12 exerted better anti-tumor activity than UDCA and had less severe side effects than fluorouracil (5-Fu). These observations indicate that U12 differs from UDCA and other derivatives and may be a suitable lead for the development of compounds useful in the treatment of HCC.

In vitro inhibition and induction of human liver cytochrome P450 enzymes by gentiopicroside: potent effect on CYP2A6

Gentiopicroside (GE), a naturally occurring iridoid glycoside, has been developed into a Novel Traditional Chinese Drug named gentiopicroside injection, and it was approved for the treatment of acute jaundice and chronic active hepatitis by SFDA. However, the inhibitory and inducible effects of GE on the activity of cytochrome P450 (CYP450) are unclear. The purpose of this study was to evaluate the ability of GE to inhibit and induce human cytochrome P450 enzymes in vitro. In human liver microsomes, GE inhibited CYP2A6 and CYP2E1 in a concentration-dependent manner, with IC₅₀ values of 21.8 µg/ml and 594 µg/ml, respectively, and the IC₅₀ of CYP2A6 was close to the C(max) value observed clinically. GE was a non-competitive inhibitor of CYP2A6 at lower concentrations and a competitive inhibitor at higher concentrations. GE did not produce inhibition of CYP2C9, CYP2D6, CYP1A2 or CYP3A4 activities. However, a significant increase of CYP1A2 and CYP3A4 activity was observed at high concentrations. In cultured human hepatocytes no significant induction of CYP1A2, CYP3A4 or CYP2B6 was observed. Given these results, the in vivo potential inhibition of GE on CYP2A6 deserves further investigation, and it seems that the hepatoprotective effect of GE is irrelevant to its effect on P450s.

Molecular mechanisms of ursodeoxycholic acid toxicity & side effects: ursodeoxycholic acid freezes regeneration & induces hibernation mode

Ursodeoxycholic acid (UDCA) is a steroid bile acid approved for primary biliary cirrhosis (PBC). UDCA is reported to have “hepato-protective properties”. Yet, UDCA has “unanticipated” toxicity, pronounced by more than double number of deaths, and eligibility for liver transplantation compared to the control group in 28 mg/kg/day in primary sclerosing cholangitis, necessitating trial halt in North America. UDCA is associated with increase in hepatocellular carcinoma in PBC especially when it fails to achieve biochemical response (10 and 15 years incidence of 9% and 20% respectively). “Unanticipated” UDCA toxicity includes hepatitis, pruritus, cholangitis, ascites, vanishing bile duct syndrome, liver cell failure, death, severe watery diarrhea, pneumonia, dysuria, immune-suppression, mutagenic effects and withdrawal syndrome upon sudden halt. UDCA inhibits DNA repair, co-enzyme A, cyclic AMP, p53, phagocytosis, and inhibits induction of nitric oxide synthatase. It is genotoxic, exerts aneugenic activity, and arrests apoptosis even after cellular phosphatidylserine externalization. UDCA toxicity is related to its interference with drug detoxification, being hydrophilic and anti-apoptotic, has a long half-life, has transcriptional mutational abilities, down-regulates cellular functions, has a very narrow difference between the recommended (13 mg/kg/day) and toxic dose (28 mg/kg/day), and it typically transforms into lithocholic acid that induces DNA strand breakage, it is uniquely co-mutagenic, and promotes cell transformation. UDCA beyond PBC is unjustified.

The impact of cholesterol and its metabolites on drug metabolism

INTRODUCTION

Global prevalence of Western-type diet has increased in the last decades resulting in occurrence of certain chronic diseases. This type of diet is also linked to high-cholesterol intake and increase in blood cholesterol. Many of the molecular mechanisms of dealing with increased levels of cholesterol and its metabolites have been elucidated in animal models and humans. It is also evident that cholesterol metabolism is closely connected to drug metabolism. Cholesterol/bile acids and drugs share many transporters, enzymes and regulatory proteins which are key points in the crosstalk.

AREAS COVERED

This review presents an overview of the effect of cholesterol and its metabolites on drug metabolism with special emphasis on species-specific differences. The article focuses on the role of nuclear receptors farnesoid X receptor, vitamin D receptor and liver X receptor in the regulation of drug metabolism genes and the role of cholesterol biosynthesis intermediates, oxysterols and bile acids in the induction of drug metabolism through pregnane X receptor.

EXPERT OPINION

Studies show that the regulation of drug metabolism by sterols is multileveled. Many species-dependent differences were observed which hinder the transfer of findings from model animals to humans. As of now, there is little evidence available for cholesterol impact on drug metabolism in vivo in humans. There is also the need to confirm the results obtained in animal models and in vitro analyses in human cells but this is very difficult given the current lack of tools.

Evaluation of the pharmacokinetic interaction of midazolam with ursodeoxycholic acid, ketoconazole and dexamethasone by brain benzodiazepine receptor occupancy

Objectives

To clarify whether alterations in midazolam pharmacokinetics resulting from changes in cytochrome P450 3A (CYP3A) activity lead to changes in its pharmacodynamic effects, benzodiazepine receptor occupancy was measured in the brain of rats after oral administration of midazolam.

Methods

Receptor occupancy was measured by radioligand binding assay in rats pretreated with ursodeoxycholic acid (UDCA), ketoconazole and dexamethasone, and the plasma concentration of midazolam was simultaneously determined.

Key findings

There was a significant increase in the apparent dissociation constant and decrease in the maximum number of binding sites for specific [3H]flunitrazepam binding after oral administration of midazolam at pharmacologically relevant doses, suggesting that midazolam binds significantly to brain benzodiazepine receptors. Pretreatment with UDCA significantly enhanced the binding. This correlated well with significant enhancement by UDCA of the plasma midazolam concentration. The brain benzodiazepine receptor binding of oral midazolam was significantly enhanced by pretreatment with ketoconazole, a potent inhibitor of CYP3A, whereas it was significantly reduced by treatment with dexamethasone, an inducer of this enzyme. These effects paralleled changes in the plasma concentration of midazolam.

Conclusions

The results indicate that pharmacokinetic changes such as altered CYP3A activity significantly influence the pharmacodynamic effect of midazolam by affecting occupancy of benzodiazepine receptors in the brain. They also suggest in-vivo or ex-vivo time-dependent measurements of receptor occupancy by radioligand binding assay to be a tool for elucidating the pharmacokinetic interaction of benzodiazepines with other agents in pre-clinical and clinical evaluations.

Ursodeoxycholic acid and tauroursodeoxycholic acid suppress choroidal neovascularization in a laser-treated rat model

PURPOSE

The aim of this study was to investigate the suppressing effects of systemically administered ursodeoxycholic acid (UDCA) and tauroursodeoxycholic acid (TUDCA) on choroidal neovascularization (CNV) in a laser-treated rat model.

METHODS

CNV was induced by argon laser photocoagulation in the right eye of each animal. UDCA 500 mg/kg, TUDCA 100 mg/kg, or vehicle was intraperitoneally injected at 24 h before and daily after laser treatment. Fourteen days after laser treatment, fluorescein angiography was performed to evaluate leakage from CNV and eyes were enucleated for histologic evaluation. Vascular endothelial growth factor (VEGF) levels in the retina were measured using enzyme-linked immunosorbent assay at 3 days after laser treatment and were compared between the UDCA, TUDCA, and control groups.

RESULTS

The proportion of CNV lesions showing clinically significant fluorescein leakage was lower in the UDCA and TUDCA groups (42%, P = 0.0124; and 46%, P = 0.0292) than in the control group (67%). CNV lesion dimensions including CNV area and CNV/choroid thickness ratio were also significantly reduced in the UDCA and TUDCA groups (7,664 +/- 630 microm(2), P < 0.001 and 8,558 +/- 570 microm(2), P < 0.001; 2.35 +/- 0.16, P = 0.026 and 2.27 +/- 0.15, P = 0.003) compared with the control group (12,147 +/- 661 microm(2) and 3.10 +/- 0.27). The VEGF level in the retina after laser treatment was lower in the TUDCA group than that in the control group (9.0 +/- 2.7 pg/mg vs. 29.4 +/- 8.2 pg/mg, P = 0.032), whereas the UDCA group showed no difference.

CONCLUSIONS

The systemic administration of UDCA and TUDCA suppressed laser-induced CNV formation in rats, which might be associated with anti-inflammatory action. The result indicates that UDCA and TUDCA are potential candidate drugs for the treatment of many CNV-related retinal diseases, including age-related macular degeneration.

Regulation of ileal bile acid-binding protein expression in Caco-2 cells by ursodeoxycholic acid: Role of the farnesoid X receptor

Ursodeoxycholic acid (UDCA) is beneficial in cholestatic diseases but its molecular mechanisms of action remain to be clearly elucidated. Other bile acids, such as chenodeoxycholic (CDCA), are agonists for the nuclear farnesoid X receptor (FXR) and regulate the expression of genes relevant for bile acid and cholesterol homeostasis. In ileal cells CDCA, through the FXR, up-regulates the expression of the ileal bile acid-binding protein (IBABP), implicated in the enterohepatic circulation of bile acids. We report that UDCA (100 and 200 microM) induced a moderate increase of IBABP mRNA (approximately 10% of the effect elicited by 50 microM CDCA) in enterocyte-like Caco-2 cells and approximately halved the potent effect of CDCA (50 microM). On the contrary, UDCA reduced by 80-90% CDCA-induced IBABP transcription in hepatocarcinoma derived HepG2 cells. We confirmed that these effects on IBABP transcription required the FXR by employing a cell-based transactivation assay. Finally, in a receptor binding assay, we found that UDCA binds to FXR expressed in CHO-K1 cells (K(d)=37.7 microM). Thus, UDCA may regulate IBABP in Caco-2 cells, which express it constitutively, by acting as a partial agonist through a FXR mediated mechanism. The observation that in HepG2 cells, which do not express constitutively IBABP, UDCA was able to almost completely prevent CDCA-induced activation of IBABP promoter, suggests that tissue-specific factors, other than FXR, may be required for bile acid regulation of FXR target genes.

Novel pathways of bile acid metabolism involving CYP3A4

The hepatic predominating cytochrome P450, CYP3A4, plays an essential role in the detoxification of bile acids and is important in pathological conditions such as cholestasis where CYP3A4 is adaptively up-regulated. However, the mechanism that triggers the up-regulation of CYP3A4 is still not clear. In this study, using recombinant CYP3A4 and human liver microsomes, we demonstrate that CYP3A4 can metabolise lithocholic acid into 3-dehydrolithocholic acid, a potent activator of the nuclear receptors, pregnane X receptor and 1,25-dihydroxy vitamin D3 receptor, which are known to regulate the expression of CYP3A4. This process thus provides a feed-forward metabolism of toxic bile acid that may be of importance in maintaining bile acid homeostasis. We also provide evidence for a novel CYP3A4-mediated metabolic pathway of the secondary bile acid deoxycholic acid. Patients treated with the antiepileptic drug carbamazepine, a CYP3A4 inducer, had markedly elevated urinary excretion of 1beta-hydroxydeoxycholic acid compared to healthy controls. The importance of CYP3A4 in this process was verified by incubations with recombinant CYP3A4 and human liver microsomes, both of which efficiently converted deoxycholic acid into 1beta-hydroxydeoxycholic acid. Interestingly, CYP3A4 was also found to be active against the secondary bile acid ursodeoxycholic acid.

No relevant effect of ursodeoxycholic acid on cytochrome P450 3A metabolism in primary biliary cirrhosis

Induction of cytochrome P450 3A (CYP3A) has been suggested as a mechanism of action of ursodeoxycholic acid (UDCA) in cholestasis. CYP3A is of key importance in human drug metabolism, being involved in presystemic extraction of more than 50% of all drugs currently available and of various endogenous compounds. Therefore, we compared the induction potential of UDCA with that of the prototypical inducer rifampicin in a human model study with the CYP3A substrates budesonide and cortisol. Twelve patients with early-stage primary biliary cirrhosis and eight healthy volunteers were treated with UDCA (15 mg/kg daily) for 3 weeks and subsequently with rifampicin (600 mg/d) for 1 week. Extensive pharmacokinetic profiling of oral budesonide (3 mg) was performed by determination of budesonide and phase I metabolites (6beta-hydroxybudesonide, 16alpha-hydroxyprednisolone) in plasma and urine at baseline and at the end of each treatment. In parallel, urinary 6beta-hydroxycortisol, a validated marker of CYP3A induction, was determined. UDCA did not affect biotransformation of budesonide and urinary excretion of 6beta-hydroxycortisol either in patients or in healthy volunteers. Ratios of areas under plasma concentration-time curves (AUC(0-12 h) during UDCA/AUC(0-12 h) before UDCA) of both metabolites were not higher than those of budesonide itself. In contrast, administration of rifampicin markedly induced CYP3A metabolism, resulting in abolished budesonide plasma levels and high urinary excretion of 6beta-hydroxycortisol. Metabolite formation was enhanced by rifampicin, but not by UDCA (e.g., AUC(16alpha-hydroxyprednisolone)/AUC(budesonide) in patients: baseline, 8.6 +/- 3.9; UDCA, 10.7 +/- 7.1; rifampicin, 527.0 +/- 248.7). In conclusion, UDCA is not a relevant inducer of CYP3A enzymes in humans.

The bile salt export pump: molecular properties, function and regulation

Secretion of bile salts from the hepatocyte into bile is the major driving force for the generation of bile flow. Identification of the bile salt export pump (BSEP, ABCB11) as the main adenosine-triphosphate-dependent bile salt transporter in mammalian liver has led to a greater understanding of the biliary bile salt secretory process and its regulation. The biology and pathobiology of BSEP have been the subject of many recent studies. Thus, it has been recognized that while mutations in the gene encoding BSEP are responsible for a subgroup of progressive familial cholestasis (progressive familial intrahepatic cholestasis subtype 2), a pediatric cholestatic disorder that may progress to cirrhosis, defective expression or function of BSEP may underlie some forms of drug-induced cholestasis. The present review summarizes recent data on the molecular properties and regulation of BSEP, as well as the clinical implications of absent or defective function of this hepatic efflux pump.

Endogenous ursodeoxycholic acid and cholic acid in liver disease due to cystic fibrosis

Focal biliary cirrhosis causes significant morbidity and mortality in cystic fibrosis (CF). Although the mechanisms of pathogenesis remain unclear, bile acids have been proposed as potential mediators of liver injury. This study examined bile acid composition in CF and assessed altered bile acid profiles to determine if they are associated with incidence and progression of liver injury in CF-associated liver disease (CFLD). Bile acid composition was determined by gas-liquid chromatography/mass spectrometry in bile, urine, and serum samples from 30 children with CFLD, 15 children with CF but without liver disease (CFnoLD), and 43 controls. Liver biopsies from 29 CFLD subjects were assessed histologically by grading for fibrosis stage, inflammation, and disruption of the limiting plate. A significantly greater proportion of endogenous biliary ursodeoxycholic acid (UDCA) was demonstrated in CFnoLD subjects vs. both CFLD subjects and controls (2.4- and 2.2-fold, respectively; ANOVA, P =.04), and a 3-4 fold elevation in endogenous serum UDCA concentration was observed in both CFLD subjects and CFnoLD subjects vs. controls (ANOVA, P <.05). In CFLD, there were significant correlations between serum cholic acid and hepatic fibrosis, inflammation, and limiting plate disruption as well as the ratio of serum cholic acid/chenodeoxycholic acid to hepatic fibrosis, inflammation, and limiting plate disruption. In conclusion, elevated endogenous UDCA in CFnoLD suggests a possible protective role against liver injury in these patients. The correlation between both cholic acid and cholic acid/chenodeoxycholic acid levels with histological liver injury and fibrosis progression suggests a potential monitoring role for these bile acids in CFLD.

Mechanisms of action and therapeutic efficacy of ursodeoxycholic acid in cholestatic liver disease

Ursodeoxycholic acid (UDCA) is widely used for the treatment of cholestatic liver diseases. Multiple mechanisms of action of UDCA have been described aiming at one or more of the pathogenetic processes of cholestatic liver diseases: (1) protection of injured cholangiocytes against toxic effects of bile acids, (2) stimulation of impaired biliary secretion, (3) stimulation of detoxification of hydrophobic bile acids, and (4) inhibition of apoptosis of hepatocytes. Through one or more of these mechanisms, UDCA slows the progression of primary biliary cirrhosis and improves a number of other cholestatic disorders.

Systematic review: ursodeoxycholic acid--adverse effects and drug interactions

BACKGROUND

Ursodeoxycholic acid is increasingly being used for the treatment of chronic cholestatic liver diseases. It appears to be generally well tolerated, but a systematic review on drug safety is lacking.

AIM

As experimental data suggest a role of bile acids in the regulation of hepatic drug metabolism at both the transcriptional and post-transcriptional level, the literature was screened for adverse drug reactions and drug interactions related to ursodeoxycholic acid.

METHODS

A systematic review of the literature was performed using a refined search strategy to evaluate the adverse effects of ursodeoxycholic acid and its interactions with other drugs.

RESULTS

Ursodeoxycholic acid caused diarrhoea in a small proportion of patients. Rare skin reactions were due to drug adjuvants rather than the active substance. Decompensation of liver cirrhosis was reported after the administration of ursodeoxycholic acid in single cases of end-stage primary biliary cirrhosis. Recurrent right upper quadrant abdominal pain was incidentally observed. The absorption of ursodeoxycholic acid was impaired by colestyramine, colestimide, colestipol, aluminium hydroxide and smectite. Metabolic drug interactions were reported for the cytochrome P4503A substrates, ciclosporin, nitrendipine and dapsone.

CONCLUSIONS

Ursodeoxycholic acid is generally well tolerated. Drug absorption interactions with anion exchange resins deserve consideration. Metabolic interactions with compounds metabolized by cytochrome P4503A are to be expected.

Cholestatic syndromes

Further insights into the cellular and molecular mechanisms underlying hepatobiliary transport function and its regulation now permit a better understanding of the pathogenesis and treatment options of cholestatic liver diseases. Identification of the molecular basis of hereditary cholestatic syndromes will result in an improved diagnosis and management of these conditions. New insights into the pathogenesis of extrahepatic manifestations of cholestasis (eg, pruritus) have facilitated new treatment strategies. Important new studies have been published about the pathogenesis, clinical features, diagnosis, and treatment of primary biliary cirrhosis, primary sclerosing cholangitis, cholestasis of pregnancy, total parenteral nutrition-induced cholestasis, drug-induced cholestasis, and viral cholestatic syndromes.