Comprehensive study of the biliary bile acid composition of patients with cystic fibrosis and associated liver disease before and after UDCA administration

Long-Term Ursodeoxycholic Acid Therapy Does Not Alter Lithocholic Acid Levels in Patients with Cystic Fibrosis with Associated Liver Disease

OBJECTIVE

To evaluate the fasting and postprandial serum bile acid composition in patients with cystic fibrosis-associated liver disease (CFLD) after chronic administration of ursodeoxycholic acid (UDCA) (20 mg/kg/day). The aim was to specifically focus on the extent of biotransformation of UDCA to its hepatotoxic metabolite, lithocholic acid, because of recent concerns regarding the safety of long-term, high-dose UDCA treatment for CFLD.

STUDY DESIGN

Twenty patients with CFLD (median age 16 years, range: 2.4-35.0) prescribed UDCA therapy for at least 2 years were studied. Total and individual serum bile acids were measured by stable-isotope dilution mass spectrometry, in fasting and 2-hour postprandial samples taken during chronic UDCA (20 mg/kg/day) administration.

RESULTS

During chronic UDCA administration (median duration 8 years, IQR: 6-16), UDCA became the predominant serum bile acid in all patients (median, IQR: 3.17, 1.25-5.56 μmol/L) and chenodeoxycholic acid concentrations were greater than cholic acid (1.86, 1.00-4.70 μmol/L vs 0.40, 0.24-2.71 μmol/L). The secondary bile acids, deoxycholate and lithocholate, were present in very low concentrations in fasted serum (<0.05 μmol/L). After UDCA administration, 2-hour postprandial concentrations of both UDCA and chenodeoxycholic acid significantly increased (P < .01), but no significant changes in serum lithocholic acid concentrations were observed.

CONCLUSION

These data do not support recent suggestions that enhanced biotransformation of UDCA to the hepatotoxic secondary bile acid lithocholic occurs when patients with CFLD are treated with relatively high doses of UDCA.

Ursodeoxycholic acid therapy in cystic fibrosis liver disease--a retrospective long-term follow-up case-control study

BACKGROUND

The prevention and treatment of liver disease associated with cystic fibrosis remain a significant unresolved problem.

AIM

To assess the long-term effects of continuous ursodeoxycholic acid (UDCA) therapy in cystic fibrosis patients with constantly elevated serum liver enzymes.

METHODS

The primary endpoint was the incidence of overt liver disease. Between 1989 and 2005, UDCA treatment was started in 98 subjects from a cohort of 382 cystic fibrosis patients. These subjects were compared with a historic control group of 352 subjects who attended our centre between 1975 and 1989 before UDCA became standard treatment. For the long-term comparison of liver function and lung function tests, a group of 98 matched contemporary cystic fibrosis patients were compared with the 98 subjects treated with UDCA.

RESULTS

Overt liver disease developed in only one of the 382 patients who was treated with UDCA for increased serum liver enzymes compared with nine patients in the historic control group (P < 0.05). Serum liver enzyme levels declined in most patients receiving UDCA treatment during the 17-year follow-up (87/98, P < 0.05). No difference was seen in lung function between subjects with cystic fibrosis-related liver disease and the matched controls.

CONCLUSIONS

Regular and systematic screening for liver involvement enables early introduction of UDCA therapy in affected cystic fibrosis patients, reduces the development of severe liver disease and leads to a significant and persistent improvement in serum liver tests, without impairing long-term pulmonary outcome.

Ursodeoxycholate modulates bile flow and bile salt pool independently from the cystic fibrosis transmembrane regulator (Cftr) in mice

Cystic fibrosis liver disease (CFLD) is treated with ursodeoxycholate (UDCA). Our aim was to evaluate, in cystic fibrosis transmembrane regulator knockout (Cftr(-/-)) mice and wild-type controls, whether the supposed therapeutic action of UDCA is mediated via choleretic activity or effects on bile salt metabolism. Cftr(-/-) mice and controls, under general anesthesia, were intravenously infused with tauroursodeoxycholate (TUDCA) in increasing dosage or were fed either standard or UDCA-enriched chow (0.5% wt/wt) for 3 wk. Bile flow and bile composition were characterized. In chow-fed mice, we analyzed bile salt synthesis and pool size of cholate (CA). In both Cftr(-/-) and controls intravenous TUDCA stimulated bile flow by ∼250% and dietary UDCA by ∼500%, compared with untreated animals (P < 0.05). In non-UDCA-treated Cftr(-/-) mice, the proportion of CA in bile was higher compared with that in controls (61 ± 4 vs. 46 ± 4%; P < 0.05), accompanied by an increased CA synthesis [16 ± 1 vs. 10 ± 2 μmol·h(-1)·100 g body wt (BW)(-1); P < 0.05] and CA pool size (28 ± 3 vs. 19 ± 1 μmol/100 g BW; P < 0.05). In both Cftr(-/-) and controls, UDCA treatment drastically reduced the proportion of CA in bile below 5% and diminished CA synthesis (2.3 ± 0.3 vs. 2.2 ± 0.4 μmol·day(-1)·100 g BW(-1); nonsignificant) and CA pool size (3.6 ± 0.6 vs. 1.5 ± 0.3 μmol/100 g BW; P < 0.05). Acute TUDCA infusion and chronic UDCA treatment both stimulate bile flow in cystic fibrosis conditions independently from Cftr function. Chronic UDCA treatment reduces the hydrophobicity of the bile salt pool in Cftr(-/-) mice. These results support a potential beneficial effect of UDCA on bile flow and bile salt metabolism in cystic fibrosis conditions.

Bile acids in treatment of ocular disease

Bear bile has been included in Asian pharmacopeias for thousands of years in treatment of several diseases, ranging from sore throat to hemorrhoids. The hydrophilic bile acids tauroursodeoxycholic acid (TUDCA) and ursodeoxycholic acid (UDCA) are the major bile acids of bear bile. Both of these are available as synthetic formulations and are approved by the health administrations of several countries for treatment of cirrhosis and gallstones. This review briefly covers the use of bear bile in Traditional Chinese Medicine, bile acid physiology, approved use of UDCA and TUDCA in Western medicine, and recent research exploring their neuroprotective properties, including in models of ocular disease.

Fibrogenesis in pediatric cholestatic liver disease: role of taurocholate and hepatocyte-derived monocyte chemotaxis protein-1 in hepatic stellate cell recruitment

Cholestatic liver diseases, such as cystic fibrosis (CF) liver disease and biliary atresia, predominate as causes of childhood cirrhosis. Despite diverse etiologies, the stereotypic final pathway involves fibrogenesis where hepatic stellate cells (HSCs) are recruited, producing excess collagen which initiates biliary fibrosis. A possible molecular determinant of this recruitment, monocyte chemotaxis protein-1 (MCP-1), an HSC-responsive chemokine, was investigated in CF liver disease and biliary atresia. The bile-duct-ligated rat and in vitro coculture models of cholestatic liver injury were used to further explore the role of MCP-1 in HSC recruitment and proposed mechanism of induction via bile acids. In both CF liver disease and biliary atresia, elevated hepatic MCP-1 expression predominated in scar margin hepatocytes, closely associated with activated HSCs, and was also expressed in cholangiocytes. Serum MCP-1 was elevated during early fibrogenesis. Similar observations were made in bile-duct-ligated rat liver and serum. Hepatocytes isolated from cholestatic rats secreted increased MCP-1 which avidly recruited HSCs in coculture. This HSC chemotaxis was markedly inhibited in interventional studies using anti-MCP-1 neutralizing antibody. In CF liver disease, biliary MCP-1 was increased, positively correlating with levels of the hydrophobic bile acid, taurocholate. In cholestatic rats, increased MCP-1 positively correlated with taurocholate in serum and liver, and negatively correlated in bile. In normal human and rat hepatocytes, taurocholate induced MCP-1 expression.

CONCLUSION

These observations support the hypothesis that up-regulation of hepatocyte-derived MCP-1, induced by bile acids, results in HSC recruitment in diverse causes of cholestatic liver injury, and is a key early event in liver fibrogenesis in these conditions. Therapies aimed at neutralizing MCP-1 or bile acids may help reduce fibro-obliterative liver injury in childhood cholestatic diseases.

Bile acids for viral hepatitis

BACKGROUND

Trials have assessed bile acids for patients with viral hepatitis, but no consensus has been reached regarding their usefulness.

OBJECTIVES

To assess the beneficial and harmful effects of bile acids for viral hepatitis.

SEARCH STRATEGY

Searches were performed in The Cochrane Hepato-Biliary Group Controlled Trials Register (July 2007), The Cochrane Library (Issue 1, 2007), MEDLINE (July 2007), EMBASE (July 2007), Science Citation Index Expanded (July 2007), and Chinese Biomedical Database (July 2007).

SELECTION CRITERIA

Randomised clinical trials comparing any dose or duration of bile acids versus placebo or no intervention for viral hepatitis were included, irrespective of language, publication status, or blinding. Co-interventions were allowed in the included randomised clinical trials.

DATA COLLECTION AND ANALYSIS

Two authors extracted the data independently. The methodological quality of the trials was evaluated with respect to generation of the allocation sequence, allocation concealment, double blinding, and follow-up. The outcomes were presented as relative risks (RR) or weighted mean differences (WMD) with 95% confidence intervals (CI).

MAIN RESULTS

We identified 29 randomised trials of bile acids for hepatitis B or C; none were of high methodological quality. We were unable to extract data from two trials. In one trial, ursodeoxycholic acid (UDCA) versus placebo for acute hepatitis B significantly reduced the risk of hepatitis B surface antigen positivity at the end of treatment and serum HBV DNA level at the end of follow-up. In another trial, UDCA versus no intervention for chronic hepatitis B significantly reduced the risk of having abnormal serum transaminase activities at the end of treatment. Twenty-five trials compared bile acids (21 trials UDCA; four trials tauro-UDCA) versus placebo or no intervention with or without co-interventions for chronic hepatitis C. Bile acids did not significantly reduce the risk of having detectable serum HCV RNA (RR 0.99, 95% CI 0.91 to 1.07), cirrhosis, or portal and periportal inflammation score at the end of treatment. Bile acids significantly decreased the risk of having abnormal serum alanine aminotransferase activity at the end of treatment (RR 0.82, 95% CI 0.76 to 0.90) and follow-up (RR 0.91, 95% CI 0.85 to 0.98). Bile acids significantly increased the Knodell score (WMD 0.20, 95% CI 0.08 to 0.31) at the end of treatment. No severe adverse events were reported. We did not identify trials including patients with hepatitis A, acute hepatitis C, hepatitis D, or hepatitis E.

AUTHORS' CONCLUSIONS

Bile acids lead to a significant improvement in serum transaminase activities in hepatitis B and C but have no effects on the clearance of virus. There is insufficient evidence either to support or to refute effects on long-term outcomes including hepatocellular carcinoma, hepatic decompensation, and liver related mortality. Randomised trials with high methodological quality are required before clinical use is considered.

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.

Bioequivalence of a new liquid formulation of ursodeoxycholic acid (Ursofalk suspension) and Ursofalk capsules measured by plasma pharmacokinetics and biliary enrichment

BACKGROUND

Ursodeoxycholic acid is an approved therapy for hepatobiliary disorders but in infants and children compliance is compromised because it is formulated exclusively as capsules, or tablets.

AIM

To determine the pharmacokinetics and bioequivalence of a new liquid formulation of ursodeoxycholic acid (Ursofalk suspension) with a standard capsule (Ursofalk) in a randomized, unblinded, crossover designed study of 24 healthy adults.

METHODS

Equivalence was based on single bolus oral plasma pharmacokinetics and biliary ursodeoxycholic acid enrichments after repeat doses. Biliary bile acid composition and hydrophobicity index were also compared. Ursodeoxycholic acid was measured in duodenal bile by high-performance liquid chromatography and in plasma by mass spectrometry.

RESULTS

The mean percentage biliary ursodeoxycholic acid enrichment after administration of the suspension was not significantly different from that obtained with capsules (44.2 +/- 11.7% vs. 46.9 +/- 10.2%, respectively). The equivalence ratio was 0.94 (95% CI: 0.8-1.1), establishing bioequivalence between suspension and capsules. Both formulations reduced the biliary hydrophobicity index and no differences in bile acid composition were observed between formulations. The plasma pharmacokinetics of both formulations was similar and the tolerability of the suspension was excellent.

CONCLUSIONS

A new liquid formulation of ursodeoxycholic acid suitable for paediatric patients is pharmacologically bioequivalent to capsules when given as single, or repeated oral doses.

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.

Duodenogastric bile reflux is common in cystic fibrosis

BACKGROUND

Patients with cystic fibrosis (CF) have a high incidence of gastroesophageal reflux disease, but few cases of mucosal injury are reported. Duodenogastric reflux has not been studied in CF but has been suggested to have a pathogenic role in producing alkaline injury to the esophageal mucosa. The aim of this study was to analyze the presence of duodenogastric reflux in patients with CF.

PATIENTS AND METHODS

Ten patients with CF and 7 healthy volunteers participated in the study. Gastroduodenal manometry and intragastric perfusion were performed in all subjects. Gastric perfusate was analyzed for bilirubin and bile acids. Only patients and controls exhibiting normal migrating motor complexes were evaluated.

RESULTS

Eight patients with CF had normal motility recordings and had significantly higher gastric bilirubin levels compared with healthy subjects (P = 0.003). The bilirubin concentration was associated with bile acid regurgitation in five patients with CF. All bile acids were conjugated with a high glycine/taurine ratio and low levels of secondary bile acids. Small amounts of keto bile acids were found in two patients.

CONCLUSION

The patients with CF had an increased incidence of duodenogastric reflux compared with healthy subjects. The bile acid composition was typical for CF with low levels of secondary bile acids. Although high bile acid concentration was found in the duodenogastric reflux in most patients with CF, the less toxic profile of the bile acids might possibly contribute to the low frequency of Barrett's esophagus in CF.

Bile acids for viral hepatitis

BACKGROUND

The viral hepatitides are common causes of liver diseases globally. Trials have assessed bile acids for patients with viral hepatitis, but no consensus was reached regarding their usefulness.

OBJECTIVES

To assess the beneficial and harmful effects of bile acids for viral hepatitis.

SEARCH STRATEGY

Searches were performed of the trial registers of The Cochrane Hepato-Biliary Group (September 2002), The Cochrane Library (Issue 2, 2002), MEDLINE (September 2002), EMBASE (September 2002), and The Chinese Biomedical Database (April 2001).

SELECTION CRITERIA

Randomised clinical trials comparing any dose or duration of bile acids versus placebo or no intervention for viral hepatitis were included, irrespective of language, publication status, or blinding.

DATA COLLECTION AND ANALYSIS

Two reviewers extracted the data independently. The methodological quality of the trials was evaluated with respect to generation of the allocation sequence, allocation concealment, double blinding, and follow-up. The outcomes were presented as relative risks (RR) or weighted mean differences (WMD) with 95% confidence intervals (CI).

MAIN RESULTS

We identified 27 randomised trials of bile acids for hepatitis B or C; none were of high methodological quality. In one trial, ursodeoxycholic acid (UDCA) versus placebo for acute hepatitis B significantly reduced the risk of hepatitis B surface antigen positivity at the end of treatment and serum HBV DNA level at the end of follow-up. In another trial, UDCA versus no intervention for chronic hepatitis B significantly reduced the risk of having abnormal serum transaminase activities at the end of treatment. Twenty-five trials compared bile acids (21 trials UDCA; four trials tauro-UDCA) versus placebo or no intervention with or without co-interventions for chronic hepatitis C. Bile acids did not significantly reduce the risk of having detectable serum HCV RNA (RR 0.99, 95% CI 0.91 to 1.07), cirrhosis, or portal and periportal inflammation score at the end of treatment. Bile acids significantly decreased the risk of having abnormal serum alanine aminotransferase activity at the end of treatment (RR 0.82, 95% CI 0.76 to 0.90) and follow-up (RR 0.91, 95% CI 0.85 to 0.98). Bile acids significantly increased the Knodell score (WMD 0.20, 95% CI 0.08 to 0.31) at the end of treatment. No severe adverse events were reported. We did not identify trials including patients with hepatitis A, acute C, D, or E.

REVIEWER'S CONCLUSIONS

Bile acids lead to a significant improvement in serum transaminase activities in hepatitis B and C. There is insufficient evidence either to support or to refute effects on viral markers, mortality, incidence of cirrhosis, or liver histology. Trials with high methodological quality are required.

Intestinal absorption and biliary secretion of ursodeoxycholic acid and its taurine conjugate

BACKGROUND

Ursodeoxycholic acid (UDCA) and its taurine conjugate (TUDCA) exert a protective effect in cholestatic liver diseases. A greater hepatoprotective effect of TUDCA has been suggested. Absorption appears to be a limiting factor and up to now has not been studied in man.

METHODS

We studied absorption and biliary bile acid secretion and composition after administration of UDCA and TUDCA in patients who had complete extrahepatic biliary obstruction caused by pancreatic carcinoma but had no intestinal or liver disease. After 5 days of intact enterohepatic circulation eight patients with a percutaneous biliary-duodenal drainage received, during two study periods, 1000 mg (1916.9 micromol; mean 29.6 micromol kg(-1)) TUDCA and 750 mg (1910.4 micromol; mean 29.5 micromol kg(-1)) UDCA in random order. Each patient served as his own control.

RESULTS

After UDCA and TUDCA administration the biliary UDCA content increased to 55.2% and 54.6% of total bile acids, respectively (not significant). Biliary secretion of cholic and chenodeoxycholic acids remained unchanged whereas that of lithocholic acid increased slightly. A total of 64.6% of the orally administered TUDCA and 55.1% of the UDCA was absorbed (not significant). After TUDCA administration, biliary UDCA was preferentially (95.4%) taurine-conjugated whereas after UDCA administration biliary UDCA was mainly (79.8%) glycine-conjugated.

CONCLUSIONS

After oral administration of TUDCA and UDCA, no significant differences in their absorption and in biliary bile acid secretion exist. Whether biliary enrichment with taurine conjugates of UDCA instead of glycine conjugates offers advantages in the treatment of cholestatic liver disease is unclear at present.

The role of hepatic stellate cells and transforming growth factor-beta(1) in cystic fibrosis liver disease

Liver disease causes significant morbidity and mortality from multilobular cirrhosis in patients with cystic fibrosis. Abnormal bile transport and biliary fibrosis implicate abnormal biliary physiology in the pathogenesis of cystic fibrosis-associated liver disease (CFLD), yet the mediators linking biliary events to fibrosis remain unknown. Activated hepatic stellate cells (HSCs) are the pre-eminent mediators of fibrosis in a range of hepatic disorders. The dominant stimulus for matrix production by HSCs is the cytokine transforming growth factor (TGF)-beta(1). In CFLD, the role of HSCs and the source of TGF-beta(1) have not been evaluated. Liver biopsy tissue obtained from 38 children with CFLD was analyzed. Activated HSCs, identified by co-localization of procollagen alpha(1)(I) mRNA and alpha-smooth muscle actin, were demonstrated as the cellular source of excess collagen production in the fibrosis surrounding the bile ducts and the advancing edge of scar tissue. TGF-beta protein and TGF-beta(1) mRNA expression were shown to be predominantly expressed by bile duct epithelial cells. TGF-beta(1) expression was significantly correlated with both hepatic fibrosis and the percentage of portal tracts showing histological abnormalities associated with CFLD. This study demonstrates a definitive role for HSCs in fibrogenesis associated with CFLD and establishes a potential mechanism for the induction of HSC collagen gene expression through the production of TGF-beta(1) by bile duct epithelial cells.

Review article: mechanisms of action and therapeutic applications of ursodeoxycholic acid in chronic liver diseases

Ursodeoxycholic acid (ursodiol) is a non-toxic, hydrophilic bile acid used to treat predominantly cholestatic liver disorders. Better understanding of the cellular and molecular mechanisms of action of ursodeoxycholic acid has helped to elucidate its cytoprotective, anti-apoptotic, immunomodulatory and choleretic effects. Ursodeoxycholic acid prolongs survival in primary biliary cirrhosis and it improves biochemical parameters of cholestasis in various other cholestatic disorders including primary sclerosing cholangitis, intrahepatic cholestasis of pregnancy, cystic fibrosis and total parenteral nutrition-induced cholestasis. However, a positive effect on survival remains to be established in these diseases. Ursodeoxycholic acid is of unproven efficacy in non-cholestatic disorders such as acute rejection after liver transplantation, non-alcoholic steatohepatitis, alcoholic liver disease and chronic viral hepatitis. This review outlines the present knowledge of the modes of action of ursodeoxycholic acid, and presents data from clinical trials on its use in chronic liver diseases.

Intrahepatic cholestasis of pregnancy

Intrahepatic cholestasis of pregnancy is one of the primary disorders of the liver that adversely affects maternal well-being and fetal outcome. Early identification of this condition, careful interdisciplinary monitoring, and prompt delivery at fetal maturity can improve outcomes in the mother and child. Although the cause is unclear, IHCP probably arises from a genetic predisposition for increased sensitivity to estrogens and progestogens and altered membrane composition and expression of bile ducts, hepatocytes, and canalicular transport systems. As a result, the elevations in maternal levels of bile acids and their molar ratios seen in healthy pregnancy rise further in IHCP patients. Also, as the normal fetal-to-maternal transfer of bile acids across the trophoblast is impaired, the excess bile acids with abnormal profiles accumulate and are toxic to the fetus. The management of IHCP is dictated by the increased risks of fetal distress, spontaneous preterm delivery, and sudden death, as well as by alleviating pruritus in the mother. These risks to the fetus rise progressively to delivery, regardless of serum levels of bile acids and ALT. Close monitoring of these markers is essential but does not prevent sudden fetal distress and death. Provision should be made to induce labor as soon as fetal lung maturity has been established. Ursodeoxycholic acid is the only therapy that has proven effective, albeit in small studies, in alleviating pruritus and restoring towards normal the abnormal profiles of bile acids and sulfated steroids in serum and other body fluids. Ursodeoxycholic acid seems to have no obvious adverse effects on the fetus, but experience is insufficient to draw conclusions regarding teratogenicity and prevention of adverse outcomes.

Comparison of three doses of ursodeoxycholic acid in the treatment of primary biliary cirrhosis: a randomized trial

BACKGROUND/AIM

Ursodeoxycholic acid in doses of 13-15 mg x kg(-1) x day(-1), is a safe and cost-effective treatment for patients with primary biliary cirrhosis. However, very limited information exists regarding the most appropriate dose of ursodeoxycholic acid. The aim of the study was to compare three dosages of ursodeoxycholic acid with respect to changes in liver biochemistries, Mayo risk score, biliary enrichment with ursodeoxycholic acid and side effects over at least a 1-year period.

METHODS

A total of 155 patients were randomized to receive low- (5-7 mg x kg(-1) x day(-1)), standard-(13-15 mg x kg(-1) x day(-1)), and high- (23-25 mg x kg(-1) x day(-1)) doses of ursodeoxycholic acid.

RESULTS

The improvements in alkaline phosphatase (p = 0.0001), aspartate aminotransferase (p = 0.0001), Mayo risk score (p = 0.002), and ursodeoxycholic acid enrichment (p = 0.0001) were significantly greater in the standard- and high-dose groups compared to the low-dose group, but not between the standard- and high-dose groups. Changes in serum bilirubin were similar between the three groups (p = 0.07). No significant effects on symptoms were noted with any dose. No patients discontinued ursodeoxycholic acid because of side effects or toxicity.

CONCLUSIONS

Ursodeoxycholic acid in doses of 5-25 mg x kg(-1) x day(-1) is safe and well tolerated. The dose of 13-15 mg x kg(-1) x day(-1) appears to be the preferred dose for patients with primary biliary cirrhosis.

Mechanism of hepatoprotective action of bile salts in liver disease

Ursodeoxycholic acid (UDCA) improves liver enzymes and in many instances liver histology in cholestatic liver diseases such as primary biliary cirrhosis and primary sclerosing cholangitis. Besides classic cholestatic diseases, UDCA also improves liver biochemistry in alcoholic liver disease and in chronic viral hepatitis C. The main target of UDCA treatment, however, is cholestasis, and consequently the mechanisms responsible for the beneficial effects in these diseases are of interest, and are discussed in detail in this article.

Bile acid abnormalities in cholestatic liver diseases

There is ample reason to believe that UDCA is the drug of choice in cholestatic liver diseases. It is possible that UDCA has to be administered for prolonged periods to see appreciable reversal in liver damage. Nevertheless, the amelioration of symptoms and improvement in nutrition of patients are equally important. Disabling symptoms such as pruritus are often brought under control, and quality of life improves. Clearly the goal for UDCA therapy is to slow the rate of disease progression, lessen the mortality risk, and improve the quality of life in patients. It is possible that a combination therapy would be more beneficial than UDCA alone. Initial results of administering UDCA with colchicine have shown no improvement in liver histology; however, administration of UDCA together with a strong anti-inflammatory drugs may be helpful to halt immune destruction of liver cells.

Differences in the metabolism and disposition of ursodeoxycholic acid and of its taurine-conjugated species in patients with primary biliary cirrhosis

The clinical effectiveness of ursodeoxycholate in the treatment of liver disease may be limited by its poor absorption and extensive biotransformation. Because in vitro and in vivo studies suggest that the more hydrophilic bile acid tauroursodeoxycholate has greater beneficial effects than ursodeoxycholate, we have compared for the first time the absorption, metabolism, and clinical responses to these bile acids in patients with primary biliary cirrhosis (PBC). Twelve female patients with PBC were sequentially administered tauroursodeoxycholate and ursodeoxycholate (750 mg/d for 2 months) in a randomized, cross-over study. Bile acids were measured in serum, duodenal bile, urine, and feces by gas chromatography-mass spectrometry (GC-MS). Biliary ursodeoxycholate enrichment was higher during tauroursodeoxycholate administration (32.6% vs. 29.2% during ursodeoxycholate; P <.05). Lithocholic acid concentration was consistently higher in all biological fluids during ursodeoxycholate administration. Fecal bile acid excretion was the major route of elimination of both bile acids; ursodeoxycholate accounted for 8% and 23% of the total fecal bile acids during tauroursodeoxycholate and ursodeoxycholate administration, respectively (P <.05). Tauroursodeoxycholate was better absorbed than ursodeoxycholate, and, although it was partially deconjugated and reconjugated with glycine, it underwent reduced biotransformation to more hydrophobic metabolites. This comparative study suggests that tauroursodeoxycholate has significant advantages over ursodeoxycholate that may be of benefit for long-term therapy in PBC.

The choleretic effects of N-acetylglucosaminides, major urinary metabolites of ursodeoxycholic acid, in bile fistula rats

We investigated the effects of three bile acids conjugated with N-acetylglucosamine, ursodeoxycholate N-acetylglucosaminide, tauroursodeoxycholate N-acetylglucosaminide and glycoursodeoxycholate N-acetylglucosaminide, on bile flow and biliary excretion of various markers in comparison with ursodeoxycholic acid, tauroursodeoxycholic acid and glycoursodeoxycholic acid in bile fistula rats. These bile acids were infused intravenously at a constant rate of 0.3 or 0.6 micromol/min/100 g b.w. for 2 h. All bile acids examined increased bile flow in a dose-dependent manner. In particular, ursodeoxycholate N-acetylglucosaminide has a longer-lasting effect after its infusion on bile flow than the other bile acids. Furthermore, these bile acids markedly increased biliary total bile acid excretion. At a higher dose level, the coefficient of determination (r2) between the biliary total bile acid excretion and bile flow for ursodeoxycholate N-acetylglucosaminide (r2 = 0.39) was lower than that for the other bile acids (r2 = 0.75-0.92). The ursodeoxycholate N-acetylglucosaminide, as well as tauroursodeoxycholic acid, glycoursodeoxycholic acid, tauroursodeoxycholate N-acetylglucosaminide and glycoursodeoxycholate N-acetylglucosaminide, was mostly excreted in an unchanged form in bile, whereas ursodeoxycholic acid was excreted as a conjugate with taurine. The three N-acetylglucosaminides as well as ursodeoxycholic acid, tauroursodeoxycholic acid and glycoursodeoxycholic acid significantly increased the biliary excretion of cholesterol, phospholipid, bilirubin and total Ca2+. In contrast, the N-acetylglucosaminides significantly decreased in biliary bicarbonate concentration, whereas ursodeoxycholic acid significantly increased biliary bicarbonate concentration. However, tauroursodeoxycholic acid and glycoursodeoxycholic acid did not significantly change the biliary bicarbonate concentration. The results indicate that N-acetylglucosaminides have a choleretic effect in bile fistula rats. Our present study also demonstrates that N-acetylglucosaminides, but not ursodeoxycholic acid, tauroursodeoxycholic acid or glycoursodeoxycholic acid, can significantly reduce the biliary bicarbonate concentration. Furthermore, our findings suggest that ursodeoxycholate N-acetylglucosaminide may partly exert a choleretic effect via mechanisms different from those of the other bile acids.

Liver disease in cystic fibrosis

CF is a common hereditary disorder of ion transport, with increasing numbers of patients surviving beyond childhood and developing manifestations of hepatobiliary involvement. Inspissated secretions within the biliary tree result in obstruction and periductular inflammation that eventually progresses to focal and then multilobular cirrhosis. Fatty infiltration of the liver and hepatomegaly is common. Variceal hemorrhage and other findings of portal hypertension may be the initial presentation. At present, therapy with high-dose ursodeoxycholic acid should be considered standard, as it has been shown repeatedly to reduce the injurious effects of the cholestasis. Liver transplantation has been successfully performed on those with advanced disease and adequate pulmonary function. Innovative therapies for CF, including gene transfer, appear promising in preliminary studies, offering hope that earlier intervention in the course of hepatobiliary CF may soon be possible.

Effect of ursodeoxycholic acid therapy on hepatic function in children with intrahepatic cholestatic liver disease

BACKGROUND

Ursodeoxycholic acid (UDCA) has been shown to improve pruritus, alanine aminotransferase (ALT), and cholesterol levels in children with intrahepatic cholestatic liver disease. However, the effect of UDCA on quantitative tests of hepatic function in children is uncertain.

METHODS

A 2.5-year, open label, crossover study, was designed to determine the effect of UDCA (15-20 mg/kg per day for 12 months, off for 6 months, and on again for 12 months) on clinical symptoms, biochemical test results, galactose and caffeine elimination half-lives (t1/2), and quantitative hepatic scintigraphy in 13 subjects aged 13.1 +/- 2.1 years (10 of whom completed the entire study), with intrahepatic cholestasis.

RESULTS

Pruritus improved with UDCA in the 6 patients with pruritus on entry into the study. At 12 months, there was a significant decline in ALT, gamma-glutamyl transpeptidase, and plasma levels of copper and manganese, with no further decline in these levels at 24 months. There were no changes in bilirubin or cholylglycine levels. After therapy was discontinued at 12 months, UDCA was restarted within 1 month in 9 of 12 patients in response to a doubling of ALT (n = 6) or worsening pruritus (n = 3). Galactose t1/2 increased after 12 months, with no further increases after 24 months of UDCA therapy, whereas caffeine t1/2 did not change. There were no significant changes in hepatic scintigraphy throughout the study.

CONCLUSIONS

These data suggest that although UDCA therapy improves pruritus and results in a reduction in ALT and gamma-glutamyl transpeptidase, UDCA therapy did not improve quantitative measures of hepatic function in children with intrahepatic cholestasis.

Improvement of estradiol-17 beta-D-glucuronide-induced cholestasis by sodium tauroursodeoxycholate therapy in rats

BACKGROUND

Estradiol-17 beta-D-glucuronide (E-17G), a metabolite of natural estrogen, is well known to cause intrahepatic cholestasis in humans. We therefore investigated the effect of sodium tauroursodeoxycholate (T-UDCA), on E-17G-induced cholestasis in female rats.

METHODS

For the evaluation of the drug, animals given E-17G (10 mumol/kg) were divided into three groups, and T-UDCA was administered intravenously at various doses after E-17G treatment.

RESULTS

T-UDCA significantly prevented a marked reduction of bile flow in E-17G-treated rats in all experimental schedules. Furthermore, T-UDCA significantly increased in the biliary E-17G excretion rate at an early stage after E-17G treatment in rats. However, this drug caused no significant change in the biliary excretion rate of estradiol-3-sulfate-17 beta-D-glucuronide (E-3S-17G), which is identified as the major biliary metabolite with E-17G throughout the recovery periods.

CONCLUSION

These results suggest that T-UDCA can improve E-17G induced acute cholestasis by rapidly increasing the biliary E-17G excretion rate. Thus our finding may provide a useful approach for attempts to prevent drug-induced acute cholestasis in humans.

Study of human isoursodeoxycholic acid metabolism

BACKGROUND/AIMS

The aim of this study was to examine the metabolism of isoursodeoxycholic acid (isoUDCA) in humans.

METHODS

IsoUDCA was synthesized of >99% purity and administered orally for 1 week, 3 x 250 mg/day, to six healthy male subjects. Bile acids were extracted from duodenal bile, serum, and 24-h urine samples collected before and at the end of the study period, separated into groups of conjugates, and analyzed by gas chromatography-mass spectrometry and fast atom bombardment mass spectrometry.

RESULTS

IsoUDCA was tolerated without any side effect. Liver function tests did not change. Bile acid concentrations (mean+/-SEM) increased from 11.9+/-1.87 to 15.3+/-1.37 mmol/l in bile (n.s.), and from 3.4+/-0.10 to 6.8+/-0.43 micromol/l in serum (p<0.05). Urinary excretion of bile acids increased from 5.3+/-0.29 to 82.2+/-7.84 micromol/24 h (p<0.01). All changes were due to significant increases of isoUDCA and UDCA in bile, serum and urine, and of 3-dehydro-UDCA, the 3-oxo intermediate of isomerization, in bile and in serum. The relative enrichments of isoUDCA, UDCA, and 3-dehydro-UDCA, were: in bile, 2.2%, 25.7%, and 0.7%; in serum, 24.7%, 23.5%, and 6.1%; and in urine, 83.7%, 2.0%, and 2.4%. Whereas 78% of serum isoUDCA was unconjugated, 93-94% of biliary and urinary isoUDCA was conjugated with N-acetylglucosamine.

CONCLUSIONS

This study indicates good tolerance and significant intestinal absorption of orally administered isoUDCA. IsoUDCA is extensively isomerized, probably both by intestinal and hepatic enzymes to yield UDCA which became the major biliary compound. In vitro, using the human hepatoblastoma cell line Hep G2, isoUDCA was found to be cytoprotective towards ethanol-induced cell injuries.

Low-dose versus high-dose ursodeoxycholic acid in cystic fibrosis-related cholestatic liver disease. Results of a randomized study with 1-year follow-up

BACKGROUND

Ursodeoxycholic acid (UDCA) is beneficial in cholestasis related to cystic fibrosis (CF). High-dose treatment has been recommended to compensate for bile salt malabsorption. We compared the results of low-dose (10 mg/kg/day) and high-dose (20 mg/kg/day) UDCA treatment on liver biochemistry after 3 and 12 months' treatment.

METHODS

Thirty CF patients (age > 5 years) with biochemical cholestasis and compensated liver disease were randomized for low-dose (n = 17) or high-dose (n = 13) UDCA. Baseline clinical variables were comparable.

RESULTS

After 1 year one patient had died of liver failure (low dose), and three had dropped out because of pruritus (one in each group) or personal choice (low dose). In the high-dose group improvement in gamma-glutamyl transferase values was more pronounced after 3 months and 1 year (P < 0.004), and improvement of alanine aminotransferase was better after 1 yer (P < 0.02). Improvement of alkaline phosphatase and aspartate aminotransferase was comparable. Complete normalization of liver enzymes and bilirubin occurred more often in the high-dose group.

CONCLUSION

High-dose UDCA induces a better response of liver biochemistry values than low-dose UDCA in CF patients with cholestatic liver disease.

Metabolism of orally administered tauroursodeoxycholic acid in patients with primary biliary cirrhosis

The metabolism of tauroursodeoxycholic acid orally administered and its effects on the bile acid pool of patients with asymptomatic/mildly symptomatic primary biliary cirrhosis is described. Patients were randomly assigned 500, 1000, or 1500 mg/day of tauroursodeoxycholate for six months. Biliary and serum bile acids were measured before and during treatment by gas chromatography-mass spectrometry and by high performance liquid chromatography. During tauroursodeoxycholate administration, the proportion of total ursodeoxycholate in bile reached mean (SEM) 34.4 (4.5)%, 32.8 (2.8)%, and 41.6 (3.0)% with doses of 500, 1000, and 1500 mg/day, respectively. Significant decreases in the proportions of chenodeoxycholate and cholate resulted. The glycine/taurine ratio of the biliary bile acid pool decreased from 1.9 at baseline, to 1.1 with the highest dose. Ursodeoxycholate in bile was conjugated with glycine and taurine, indicating that tauroursodeoxycholate undergoes significant deconjugation and reconjugation during its enterohepatic recycling. The proportion of lithocholate in bile remained unchanged. Fasting serum conjugated ursodeoxycholate concentration positively correlated with the tauroursodeoxycholate dose, and the increased proportion of ursodeoxycholate was accompanied by substantial decreases in the endogenous bile acids. Compared with previously published data for ursodeoxycholic acid therapy, these findings indicate that the shift toward a more hydrophilic bile acid pool is greater and potentially more favourable with tauroursodeoxycholate, and this is because of the reduced intestinal biotransformation of tauroursodeoxycholate.

Biliary tract disease in children

This article discusses congenital and acquired disorders of the bile ducts and gallbladder in infants and children. Problems, such as extrahepatic biliary atresia, that are unique to infants are covered as well as distinctive aspects of hepatobiliary disease in older children. Biliary tract disease in the fetus and neonate presents an important challenge in that not only is hepatic structure and function disturbed but also the process of normal development may be retarded or altered by the disease process.

Bile acids in the assessment of hepatocellular function

Bile acids, which are synthesized in the liver from cholesterol, are important in the production of bile flow, excretion of cholesterol, and intestinal digestion and absorption of fats and fat-soluble vitamins. Increases and/or alterations in concentrations of bile acids in serum are specific and sensitive indicators of hepatobiliary disorders. Synthesis of bile acids in hepatocytes involves steps in endoplasmic reticulum, cytosol, mitochondria, and peroxisomes. Other important hepatocellular processes involving bile acids include active uptake by the basolateral membrane, intracellular transport, P-450-mediated conjugations and hydroxylations, and canalicular secretion. Hydrophobic bile acids produce hepatotoxicity in vivo and in vitro. In experimental and epidemiologic studies, some of these forms have been identified as causative agents in the development of colon and liver (experimental only) cancer. Conversely, several hydrophilic forms, primarily ursodeoxycholic acid, have demonstrated cytoprotective properties in a variety of clinical and experimental hepatobiliary diseases and disorders. Because bile acids can have dramatically different properties and effects, determination of mechanisms of action of these compounds has become an active area of research. Primary isolated hepatocytes provide an opportunity to investigate bile acid-related functions and effects in well-designed, carefully controlled studies. Short-term cultures have been used to study a variety of issues related to bile acids, including cytotoxicity, synthesis, and hepatocellular processing. With these systems, however, many functions of mature hepatocytes, including those pertaining to bile acids, can be lost when cultures are maintained for more than several days. Recent developments in culture techniques permit long-term maintenance of functionally stable, differentiated cells. Pertaining to bile acid research, these systems remain to be fully characterized but, in appropriate situations, they should provide important alternatives to in vivo studies and short-term in vitro assays.

The site-specific delivery of ursodeoxycholic acid to the rat colon by sulfate conjugation

BACKGROUND & AIMS

Because ursodeoxycholate has been shown to act as a tumor-suppressive agent in the colon, the absorption and metabolism of its sulfate conjugates were examined in rats to show that sulfation would facilitate the site-specific delivery of ursodeoxycholate to the colon.

METHODS

Bile acids were measured in intestinal contents, feces, urine, plasma, and liver tissue after oral administration of ursodeoxycholate and its C-3, C-7, and C-3,7 sulfate derivatives.

RESULTS

Ursodeoxycholate was found in the jejunum after administration of all bile acids, but the mass was greatest for ursodeoxycholic acid administration. In the colon, lithocholic acid, normally found in negligible amounts, became the major bile acid after ursodeoxycholate administration. In contrast, reductions in mass and proportions of lithocholate and deoxycholate occurred after administering the C-7 sulfates. The fecal lithocholate/deoxycholate ratio, a risk marker for colon cancer, increased markedly after administration of ursodeoxycholate and its C-3 sulfate, but did not change after administering the C-7 sulfates. Unlike ursodeoxycholate or its C-3 sulfate, which increased liver concentrations of lithocholate and ursodeoxycholate, the C-7 sulfates had the opposite effect, which was consistent with poor absorption.

CONCLUSIONS

Sulfation of ursodeoxycholate, specifically at the C-7 position, protects the molecule from bacterial degradation and inhibits its intestinal absorption, thereby facilitating delivery to the colon.

Tauroursodeoxycholate increases rat liver ursodeoxycholate levels and limits lithocholate formation better than ursodeoxycholate

BACKGROUND & AIMS

To explain the greater hepatoprotective effect of tauroursodeoxycholic acid vs. ursodeoxycholic acid, the absorption, hepatic enrichment, and biotransformation of these bile acids (250 mg/day) were compared in rats.

METHODS

Bile acids were determined in intestinal contents, feces, urine, plasma, and liver by gas chromatography-mass spectrometry.

RESULTS

The concentration of ursodeoxycholate in the liver of animals administered tauroursodeoxycholic acid (175 +/- 29 nmol/g) was greater (P < 0.05) than in animals administered ursodeoxycholic acid (79 +/- 19 nmol/g). Hepatic lithocholate was substantially higher after ursodeoxycholic acid administration (21 +/- 10 nmol/g) than after tauroursodeoxycholic acid administration (12 +/- 1 nmol/g). A concomitant reduction in the proportion of hydrophobic bile acids occurred that was greatest during tauroursodeoxycholic acid administration. In the intestinal tract, the mass of ursodeoxycholate and its specific metabolites was greater in rats administered tauroursodeoxycholic acid (27.2 mg) than those administered ursodeoxycholic acid (13.2 mg). In feces, the proportion of lithocholate was 21.9% +/- 4.9% and 5.4% +/- 4.0% after ursodeoxycholic acid and tauroursodeoxycholic acid administration, respectively.

CONCLUSIONS

Compared with ursodeoxycholic acid, tauroursodeoxycholic acid induces a greater decrease in the percent composition of more hydrophobic bile acids within the pool, limits lithocholate formation, and increases hepatic ursodeoxycholate concentration. These differences are explained by increased hepatic extraction and reduced intestinal biotransformation and not by enhanced absorption of the amidated species.

Ursodeoxycholic acid therapy of chronic cholestatic conditions in adults and children

Cholestasis can be defined as the manifestation of defective bile acid transport from the liver to the intestine. Most chronic cholestatic conditions can progress towards cirrhosis. At this stage, liver transplantation is the treatment of choice. Most of the drugs so far evaluated show some degree of efficacy but have major side effects. Given that ursodeoxycholic acid (UDCA) has no apparent toxicity in humans, it was postulated that long-term treatment with this drug might displace endogenous bile acids and thus reverse their suspected toxicity. We demonstrated that long-term UDCA therapy slows the progression of primary biliary cirrhosis and reduces the need for liver transplantation. In this review, we give the rationale for the use of UDCA in cholestasis and discuss its possible mechanisms of action. We also give an overview of current data on UDCA therapy of chronic cholestatic disorders in adults and children.

Ursodeoxycholic acid in the treatment of primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a cholestatic liver disease characterized by inflammation and obliterative fibrosis of bile ducts leading to their progressive destruction (1-4). As a consequence, cholestasis with elevated serum levels of alkaline phosphatase (AP) and gamme glutamyl transpeptidase (GGT) and bilirubin in more advanced disease is the most prominent feature of this disease. The diagnosis of PSC is primarily based on endoscopic retrograde cholangiography with demonstration of irregular strictures and dilatations. In liver biopsy, typical findings are portal and periodical inflammation and fibrosis. Since PSC is a focal disease, the characteristic histological findings may or may not be seen in a single liver biopsy. The cause of PSC is still unknown. The association with histocombatibility antigens indicates that immunological mechanisms may be involved but it is still unclear whether the disease is immunogenic. Alternatively, bacteria and bacterial toxins from the colon might play a role (3, 4). In 70% of cases PSC is associated with ulcerative colitis (5) and, therefore, in all patients with this intestinal disease who also have elevated levels of liver enzymes, a cholangiography should be performed. Recently, in up to 80% of patients with PSC anti-neutrophil-cytoplasmatic-antigens (ANCA) were found to be elevated (6) and, in future, this test may help to diagnose the disease more easily. Up to now, however, the disease is usually diagnosed at a relatively advanced stage when the patients have jaundice.

The major metabolites of ursodeoxycholic acid in human urine are conjugated with N-acetylglucosamine

Ursodeoxycholic acid (750 mg/day) was administered orally to ten healthy subjects over a period of 10 days; 24 hr urine samples were collected the day before and on the last day of the study. Urinary bile acids were extracted, separated into groups of conjugates and analyzed by gas chromatography-mass spectrometry and fast atom bombardment mass spectrometry. Excretion of ursodeoxycholic acid rose from 70 to 2,915 micrograms/24 h. The highest increase was observed among N-acetylglucosamine conjugates, 90% of which constituted the previously unknown double conjugate of ursodeoxycholic acid with N-acetylglucosamine and glycine. Excretion of isoursodeoxycholic acid increased from 50 to 738 micrograms/24 h. This isomerization product of ursodeoxycholic acid was excreted almost exclusively as N-acetylglucosamine conjugate. In total, N-acetylglucosamine conjugates constituted 50% of urinary metabolites of ursodeoxycholic acid. In addition, metabolites of ursodeoxycholic acid hydroxylated at carbon atoms 1, 6, 22 and possibly 21 were observed. These compounds were also found as conjugates with N-acetylglucosamine. Their formation from ursodeoxycholic acid was definitely demonstrated by 13C-labeling after giving [24-13C]ursodeoxycholic acid to one of the healthy subjects and to a patient with extrahepatic cholestasis in whom hydroxylation of ursodeoxycholic acid at C-23 was also observed. The patient was also found to excrete the double conjugate of ursodeoxycholic acid with N-acetylglucosamine and taurine. The N-acetylglucosaminidation of ursodeoxycholic acid in vivo was shown to occur at C-7.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphologic changes in livers of hamsters treated with high doses of ursodeoxycholic acid: correlation with bile acids in bile

The effects of high doses of ursodeoxycholic acid on bile acid composition and the liver morphology was examined in 60 male Syrian golden hamsters. The animals were allocated to five groups: I, control; II and IV received 0.5 g and 1 g of ursodeoxycholic acid per 100 g of standard diet respectively over 30 days and III and V received 0.5 g and 1 g of ursodeoxycholic acid per 100 g of standard diet respectively over 60 days. Bile acids were determined by high performance liquid chromatography. In all treated groups there was a significant increase in chenodeoxycholic and lithocholic acid in the bile. The mean glyco/tauro ratio was significantly higher than in the control group, reaching values > 1 for individual bile acids, except for lithocholic acid values which remained < 1. Under light microscopy, the livers of the hamsters showed damage which was dose/time related, namely portal inflammatory infiltrate, bile duct proliferation, cholestasis, fat infiltration and necrosis. Electron microscopy revealed pronounced changes starting with microvilli edema and extending to canalicular membrane destruction and necrosis. The changes observed in the relation glyco/tauro lithocholic acids, may be due to defence mechanisms to avoid hepatotoxicity. The hepatotoxicity resulting from ursodeoxycholic acid administration is presumed to be due primarily to lithocholic acid or some lithocholic acid metabolite.

Cystic fibrosis. Is treatment with ursodeoxycholic acid of value?

Liver and biliary diseases are common complications in cystic fibrosis (CF) and may even be so severe that liver transplantation is indicated in cases with mild pulmonary disease. The most common complications are steatosis, fibrosis/cirrhosis, micro gallbladder, cholelithiasis, and sclerosing cholangitis. Ursodeoxycholic acid (UDCA) has been used in the treatment of gallstones and pathological liver function in CF. The effect on gallstones has been contradictory, and the effect on liver function tests has been shown to be dose-dependent. A significantly better effect has been shown on liver function tests during treatment over 1 year with doses of 15-20 mg/kg/day. Although supplementation with taurine did not further improve this effect, it has been used in many studies. The biliary bile acid pool was enriched by UDCA from about 10% to 35-40%, but a similar increase was not seen in serum. We have studied the long-term effect of UDCA in 10 patients with liver fibrosis or cirrhosis and/or sclerosing cholangitis. Liver function and liver morphology examined on liver biopsies by both light and transmission electron microscopy (TEM) were followed for 2 years. Preliminary results of this study are encouraging. UDCA is an interesting drug which binds to the hepatocyte membranes, stabilizing membrane structure in in vitro experiments and increasing the bicarbonate excretion in bile in pigs. The mechanism of the effect of UDCA in CF might not only be an increased choleresis; further studies will focus on these aspects.

Ursodeoxycholic acid improves ethinyl estradiol-induced cholestasis in the rat

The effect of oral chronic administration of ursodeoxycholic acid has been examined in rats with cholestasis induced by ethinyl estradiol. Ursodeoxycholic acid at the dose of 25 mg kg-1 per day during 4 days, did not improve the decrease in basal bile flow and bile acid secretion induced by ethinyl estradiol alone. In contrast, when ursodeoxycholic acid was given at the same dose during 10 days, basal bile flow was significantly improved and basal bile acid secretion was restored to control values. When ursodeoxycholic acid was given at the dose of 500 mg kg-1 per day, basal bile flow and bile acid output were not further improved. However, bile flow and bile acid output under taurocholate infusion were restored to control values. Bile of rats treated with ursodeoxycholic acid was enriched with this bile acid. These results show a significant improvement of ethinyl estradiol-induced cholestasis in rats after chronic administration of ursodeoxycholic acid and support the use of this bile acid in intrahepatic cholestasis in man.

Ursodiol in the long-term treatment of chronic hepatitis: a double-blind multicenter clinical trial

Ursodeoxycholic acid (UDCA or ursodiol) administration has been associated with a reduction of serum liver enzymes in patients with chronic liver disease and with improvement of liver histology in patients with primary biliary cirrhosis. To establish the potential therapeutic efficacy of ursodiol in chronic hepatitis, serum biochemistry and liver histology were investigated in a multicenter, double-blind placebo controlled clinical trial. Sixty patients with non-cholestatic chronic active (mild or severe) hepatitis, mainly of viral (virus C) etiology and almost completely asymptomatic, were enrolled in 3 centers: 29 were assigned to receive placebo and 31 UDCA (600 mg/day) for 1 year. Demographic, biochemical, virological and histological features were balanced between the 2 groups at the entrance into the study. Fifty-six patients (34 males, 22 females; 19 with cirrhosis; 5 HBsAg-positive; 45 anti-HCV positive) were included in the final analysis. Compliance was checked by measuring UDCA levels at the 3 follow-up visits (3, 6 and 12 months). Liver biopsy was performed at the beginning and at the end of treatment and was evaluated blindly by our pathologist (F.C.). Alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gammaglutamyltransferase (GGT) levels were significantly reduced by 25% from baseline values during treatment with ursodiol but not with placebo. The efficacy of UDCA in lowering serum AST and ALT was more pronounced in the presence of cirrhosis. The semiquantitative liver histological score used remained substantially unchanged after treatment and no differences between placebo and UDCA were found for portal or periportal necrosis or inflammation, intralobular degeneration, cholestasis or fibrosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of ursodeoxycholic acid on the kinetics of cholic acid and chenodeoxycholic acid in patients with primary sclerosing cholangitis

Treatment of patients with cholestatic liver diseases with ursodeoxycholic acid has been shown to have beneficial effects that may be related to a shift in the balance between hydrophilic and hydrophobic bile acids in favor of hydrophilic bile acids. During treatment of patients with primary sclerosing cholangitis with ursodeoxycholic acid, plasma concentrations of some endogenous bile acids decrease. To test whether the changes in plasma bile acids are due to decreases of their pool sizes or synthesis rates, we determined bile acid kinetics of cholic and chenodeoxycholic acid in six patients with primary sclerosing cholangitis, of whom four also had ulcerative colitis. All patients were studied before and 3 mo after the start of ursodeoxycholic acid treatment. Six healthy subjects served as controls. In patients with primary sclerosing cholangitis, pool sizes of cholic and chenodeoxycholic acid were considerably smaller than those in healthy controls; after ursodeoxycholic acid treatment they were unchanged. Fractional turnover and synthesis of cholic acid increased significantly after ursodeoxycholic acid administration. Fractional turnover of chenodeoxycholic acid also increased significantly, whereas synthesis of this bile acid was unchanged. Our data indicate that in patients with primary sclerosing cholangitis, pool sizes of bile acids are reduced. The decrease of levels of endogenous bile acids in plasma under ursodeoxycholic acid treatment despite unchanged bile acid pool sizes indicates redistribution of the bile acids into the enterohepatic circulation, probably because of improved hepatic clearance after ursodeoxycholic acid treatment.

Biotransformation of orally administered ursodeoxycholic acid in man as observed in gallbladder bile, serum and urine

The aim of this study was to evaluate the biotransformation of orally administered ursodeoxycholic acid in man. The distribution of ursodeoxycholic acid and its metabolites in gallbladder bile, in serum and in urine with emphasis on separation of their unconjugated, amidated and sulfated species in particular, was investigated. Seven gallstone patients were given 750 mg of ursodeoxycholic acid daily for 2-3 weeks. Six gallstone patients who did not receive ursodeoxycholic acid served as controls. Ursodeoxycholic acid became the major bile acid in gallbladder bile contributing 43% to total bile acids. 2% of biliary ursodeoxycholic acids were in the unconjugated form, 87% in the amidated form and 11% in the sulfated form. Iso-ursodeoxycholic acid was found in bile in small amounts and was present only as the sulfated species and not as the amidated one. Other metabolites of ursodeoxycholic acid tentatively identified in bile were 1 beta, 12 beta, 6 alpha- and 21,22-hydroxylated derivatives of ursodeoxycholic acid. Lithocholic acid in bile tended to increase under ursodeoxycholic acid treatment and was positively correlated to ursodeoxycholic acid. The concentration of cholic acid in bile decreased significantly whereas the levels of deoxycholic acid and chenodeoxycholic acid did not change. Total bile acid concentration in serum and excretion of bile acids in urine increased from 5.4 +/- 1.1 to 18.4 +/- 9.5 mumol l-1 (mean +/- SD, P < 0.005) and from 5.6 +/- 1.3 to 13.1 +/- 7.9 mumol g-1 creatinine (mean +/- SD, P < 0.05) after ursodeoxycholic acid ingestion mainly due to spillover and excretion of ursodeoxycholic acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Cystic fibrosis

Cystic fibrosis, an autosomal recessive disorder, is the most common genetic disease of Caucasians. One in 25 Caucasians are carriers of the gene. The gene is found far less commonly in other races. There are over 230 different alleles of the gene, located on the 7th chromosome. The gene encodes for a membrane protein that functions as an ion channel. The survival of cystic fibrosis patients has been gradually increasing, with a mean survival in 1990 of 28 years. If the current trend of improved survival continues, it is estimated that half of cystic fibrosis patients will be over 18 years old by 1996. Disease is found in many organs including the lungs, sinuses, pancreas, gastrointestinal tract, hepatobiliary system, sweat glands and reproductive tract. The majority of patients die of pulmonary disease. The airways become chronically colonized with bacteria that cannot be eradicated, leading to bronchitis, bronchiectasis, and finally, pulmonary fibrosis with respiratory failure. The pulmonary disease may be complicated by massive hemoptysis and pneumothorax. Patient survival rates have increased because of antibiotic therapy and improved nutrition with pancreatic enzyme replacements. New treatments for the pulmonary disease are under clinical trial and include antiproteases, amiloride, a sodium channel blocker, and DNase. The insertion of the normal cystic fibrosis allele into an animal model using a modified adenovirus with effective transcription suggests that gene therapy may be possible in the future, but safety and technical problems have to be addressed.

Ursodeoxycholic acid therapy in cystic fibrosis-associated liver disease: a dose-response study

Previous studies from our groups have demonstrated improvements in biochemical markers of liver function when cystic fibrosis patients with associated liver disease were administered oral ursodeoxycholic acid. The magnitude of the response was somewhat less than that found when comparable doses (10 to 15 mg/kg body wt/day) of ursodeoxycholic acid are given to other liver disease patients; this may be explained by the bile acid malabsorption that is characteristic of the disease. For this reason a dose-response study was carried out in nine cystic fibrosis patients with liver disease to establish whether improved efficacy could be obtained with higher doses. Ursodeoxycholic acid in doses of 5, 10 and 15 mg/kg body wt/day was given orally for consecutive 2-mo periods in a replicated Latin-square design. After this, all patients received 20 mg/kg body wt/day. Liver function, individual serum bile acids and biliary bile acid composition were determined at entry and at the end of each treatment period. Our data demonstrate that the magnitude of the biochemical improvement in serum liver enzymes was significantly greater with higher doses of ursodeoxycholic acid; at 20 mg/kg body wt/day it was similar to that reported for patients with other liver diseases administered lower doses. Biliary ursodeoxycholic acid enrichment increased with increasing doses, attaining 42% +/- 6% of the total biliary bile acids with the highest dose. Fasting serum ursodeoxycholic acid concentrations increased during ursodeoxycholic acid administration but were variable and correlated poorly with the dose of ursodeoxycholic acid administered, whereas no correlation was found between serum ursodeoxycholic acid concentration and the proportion of ursodeoxycholic acid in bile.(ABSTRACT TRUNCATED AT 250 WORDS)

Bile acid N-acetylglucosaminidation. In vivo and in vitro evidence for a selective conjugation reaction of 7 beta-hydroxylated bile acids in humans

The aim of this study was to define whether N-acetylglucosaminidation is a selective conjugation pathway of structurally related bile acids in humans. The following bile acids released enzymatically from N-acetylglucosaminides were identified: 3 alpha,7 beta-dihydroxy-5 beta-cholanoic (ursodeoxycholic), 3 beta, 7 beta-dihydroxy-5 beta-cholanoic (isoursodeoxycholic), 3 beta,7 beta-dihydroxy-5 alpha-cholanoic (alloisoursodeoxycholic), 3 beta,7 beta-dihydroxy-5-cholenoic, 3 alpha,7 beta,12 alpha-trihydroxy-5 beta-cholanoic, and 3 alpha,6 alpha,7 beta-trihydroxy-5 beta-cholanoic acids. The selectivity of conjugation was studied by administration of 0.5 g ursodeoxycholic (UDCA) or hyodeoxycholic (HDCA) acids, labeled with 13C, to patients with extrahepatic cholestasis, and of 0.5 g of 13C-labeled chenodeoxycholic acid (CDCA) to patients with extra- or intrahepatic cholestasis. After administration of [24-13C]-CDCA, labeled glucosides, and the glucuronide of CDCA were excreted in similar amounts. Labeled N-acetylglucosaminides of UDCA and isoUDCA were also formed. When [24-13C]-UDCA was given, 13C-label was detected in the N-acetylglucosaminide, the glucosides, and the glucuronide of UDCA, and in the N-acetylglucosaminide of isoUDCA. In the patient studied, 32% of the total UDCA excreted in urine was conjugated with N-acetylglucosamine. In contrast, 96% of the excreted amount of [24-13C]HDCA was glucuronidated, and 13C-labeled glucosides but no N-acetylglucosaminide were detected. The selectivity of N-acetylglucosaminidation towards bile acids containing a 7 beta-hydroxyl group was confirmed in vitro using human liver and kidney microsomes and uridine diphosphate glucose (UDP)-N-acetylglucosamine. These studies show that N-acetylglucosaminidation is a selective conjugation pathway for 7 beta-hydroxylated bile acids.

Bile acid biosynthesis

To conclude, the last several years have seen a resurgence of interest in the biosynthesis of bile acids. This focus has come about due to the central roles that these molecules play in cholesterol and fat metabolism and due to recent advances in their chemistry, biochemistry, and molecular biology. The application of probes generated by these methodologies has begun to generate novel insight into bile acid metabolism, regulation, and genetics. The next several years should be equally exciting.

Scintigraphic documentation of an improvement in hepatobiliary excretory function after treatment with ursodeoxycholic acid in patients with cystic fibrosis and associated liver disease

We have previously documented that ursodeoxycholic acid exerts a beneficial effect on liver function and bile acid metabolism in patients with cystic fibrosis. We hypothesized that the mechanism of action may be related in part to the choleretic properties of the administered bile acid. We therefore compared hepatobiliary scintigraphic images obtained before and 1 yr after initiation of ursodeoxycholic acid therapy to document an improvement in bile flow in 13 patients with cystic fibrosis and hepatobiliary involvement. Before therapy, hepatobiliary scintigraphy documented biliary stasis with retention of the isotope in intrahepatic and extrahepatic bile ducts in nine patients; during therapy, duct dilatation decreased substantially in eight patients, with decreased intrahepatic retention and more rapid biliary outflow of the tracer. The time of appearance of isotope in the intestine decreased (from a mean of 36.9 +/- 17.8 min to 18.8 +/- 9.0 min; p less than 0.01) in all patients in whom it had been abnormal, and the half-time of hepatic washout decreased from a mean of 35 +/- 20.7 min to 26 +/- 15.6 min (p less than 0.05). During ursodeoxycholic acid administration enrichment of bile was achieved, with the mean ursodeoxycholic acid percent composition increasing from 5.8% +/- 2.9% to 35.7% +/- 8.5%. Ursodeoxycholic acid became the predominant bile acid in serum. Liver function improved in all 10 of the patients with abnormal values at baseline. We conclude that hepatobiliary scintigraphy is of value in monitoring the therapeutic responses of cystic fibrosis patients with liver disease to ursodeoxycholic acid therapy.(ABSTRACT TRUNCATED AT 250 WORDS)