Ursodeoxycholic acid vs. chenodeoxycholic acid as cholesterol gallstone-dissolving agents: a comparative randomized study

The Conservative Management of Choledocholithiasis With Ursodeoxycholic Acid

Choledocholithiasis has been defined as the presence of stones within the common bile duct (CBD) with up to one-half of the cases remaining asymptomatic. We report a case of an 84-year-old frail male admitted for the treatment of pneumonia, pleural effusion, and bacteraemia with co-incidental deranged liver function tests (LFTs). Ensuing magnetic resonance cholangiopancreatography (MRCP) noted three CBD stones; however, the patient remained asymptomatic. After discussing the benefits and risks of treatment options with the gastroenterology team, the patient refused endoscopic retrograde cholangiopancreatography (ERCP) and opted for close monitoring in the community whilst taking ursodeoxycholic acid (UDCA). In the months following, his LFTs normalised, and repeat MRCP no longer showed stones. This case demonstrates that UDCA with close monitoring may be considered a non-invasive alternative treatment of CBD stones, particularly in elderly or frail patients with multiple comorbidities.

Reconstruction of Acinetobacter johnsonii ICE_NC genome using hybrid de novo genome assemblies and identification of the 12α-hydroxysteroid dehydrogenase gene

AIMS

The role of a Acinetobacter johnsonii strain, isolated from a soil sample, in the biotransformation of bile acids (BAs) was already described but the enzymes responsible for these transformations were only partially purified and molecularly characterized.

METHODS AND RESULTS

This study describes the use of hybrid de novo assemblies, that combine long-read Oxford Nanopore and short-read Illumina sequencing strategies, to reconstruct the entire genome of A. johnsonii ICE_NC strain and to identify the coding region for a 12α-hydroxysteroid dehydrogenase (12α-HSDH), involved in BAs metabolism. The de novo assembly of the A. johnsonii ICE_NC genome was generated using Canu and Unicycler, both strategies yielded a circular chromosome of about 3.6 Mb and one 117 kb long plasmid. Gene annotation was performed on the final assemblies and the gene for 12α-HSDH was detected on the plasmid.

CONCLUSIONS

Our findings illustrate the added value of long read sequencing in addressing the challenges of whole genome characterization and plasmid reconstruction in bacteria. These approaches also allowed the identification of the A. johnsonii ICE_NC gene for the 12α-HSDH enzyme, whose activity was confirmed at the biochemical level.

SIGNIFICANCE AND IMPACT OR THE STUDY

At present, this is the first report on the characterization of a 12α-HSDH gene in an A. johnsonii strain able to biotransform cholic acid into ursodeoxycholic acid, a promising therapeutic agent for several diseases.

Contributions of bile acids to gastrointestinal physiology as receptor agonists and modifiers of ion channels

Bile acids (BAs) are known to be important regulators of intestinal motility and epithelial fluid and electrolyte transport. Over the past two decades, significant advances in identifying and characterizing the receptors, transporters, and ion channels targeted by BAs have led to exciting new insights into the molecular mechanisms involved in these processes. Our appreciation of BAs, their receptors, and BA-modulated ion channels as potential targets for the development of new approaches to treat intestinal motility and transport disorders is increasing. In the current review, we aim to summarize recent advances in our knowledge of the different BA receptors and BA-modulated ion channels present in the gastrointestinal system. We discuss how they regulate motility and epithelial transport, their roles in pathogenesis, and their therapeutic potential in a range of gastrointestinal diseases.

An Overview of 7α- and 7β-Hydroxysteroid Dehydrogenases: Structure, Specificity and Practical Application

7α-Hydroxysteroid dehydrogenase and 7β-hydroxysteroid dehydrogenase are key enzymes involved in bile acid metabolism. They catalyze the epimerization of a hydroxyl group through 7-keto bile acid intermediates. Basic research of the two enzymes has focused on exploring new enzymes and the structure-function relationship. The application research focused on the in vitro biosynthesis of bile acid drugs and the exploration and improvement of their catalytic ability based on molecular engineering. This article summarized the primary and advanced structural characteristics, specificities, biochemical properties, and applications of the two enzymes. The emphasis is also given to obtaining of novel 7α-hydroxysteroid dehydrogenase and 7β-hydroxysteroid dehydrogenase that are thermally stable and active in the presence of organic solvents, high substrate concentration, and extreme pH values. To achieve these goals, enzyme redesigning based on protein engineering and genomics may be the most useful approaches.

An effective synthesis of ursodeoxycholic acid from dehydroepiandrosterone

A novel synthetic route of producing ursodeoxycholic acid (UDCA) was developed through multiple reactions from plant-source dehydroepiandrosterone (DHEA), with a Mistunobu reaction and regioselective allyl oxidationat as the key steps. The reaction conditions of the key allyl oxidation reaction were also investigated and optimized, including solvent, oxidant and reaction temperature. In this novel route for the preparation of UDCA, most of the reaction steps have high conversions and overall yield up to 35% for 8 steps. Since all starting materials are cost-effective, commercially available and effectively avoided the risk of animal derived raw materials, this promising synthetic route offers economical and efficient strategies for potential production of UDCA.

Global profiling and identification of bile acids by multi-dimensional data mining to reveal a way of eliminating abnormal bile acids

Bile acids (BAs), as crucial endogenous metabolites, are closely related to cholestasis, metabolic disorders, and cancer. To better understand their function and disease pathogenesis, global profiling of BAs is necessary. Here, multidimensional data mining was developed for the discovery and identification of potentially unknown BAs in cholestasis rats. Based on an in-house theoretical BA database and using a newly established liquid chromatography-tandem high-resolution mass spectrometry (LC-HRMS/MS) method, four-dimensional (4D) data including the retention times (RT), abundances, HRMS, and HRMS/MS spectra were acquired and elucidated. And 491 BAs were totally profiled. Then, the relationships between RT with different conjugation types, different positions and configurations of hydroxyl/ketone groups as well as fragmentation rules of hydroxyl, ortho-hydroxyl, ketone, and conjugated groups of BAs were summarized to assist BA identification for the first time. Finally, 292 BAs were assigned with molecular formulas, 201 of which were putatively identified by integrating the 4D data, applying structure-driven relative retention time rules, and a comparison with synthetic BAs. The estimated concentrations of 201 BAs, including 93 reported and 108 newly identified BAs, were quantified by using surrogate standards with similar structure. Among 201 BAs, 38 BAs were detected in both humans and rats for the first time. Our strategy has expanded the scope of BAs and provides a way to identify a class of metabolites. Compared to normal rats, the significantly increased sulfated and glucuronide conjugated BAs in urine and feces from experimentally cholestatic rats may reveal a way to diagnose intrahepatic cholestasis.

Highly selective bile acid hydroxylation by the multifunctional bacterial P450 monooxygenase CYP107D1 (OleP)

OBJECTIVE

Regio- and stereoselective hydroxylation of lithocholic acid (LCA) using CYP107D1 (OleP), a cytochrome P450 monooxygenase from the oleandomycin synthesis pathway of Streptomyces antibioticus.

RESULTS

Co-expression of CYP107D1 from S. antibioticus and the reductase/ferredoxin system PdR/PdX from Pseudomonas putida was performed in Escherichia coli whole cells. In vivo hydroxylation of LCA exclusively yielded the 6β-OH product murideoxycholic acid (MDCA). In resting cells, 19.5% of LCA was converted to MDCA within 24 h, resulting in a space time yield of 0.04 mmol L^-1 h^-1. NMR spectroscopy confirmed the identity of MDCA as the sole product.

CONCLUSIONS

The multifunctional P450 monooxygenase CYP107D1 (OleP) can hydroxylate LCA, forming MDCA as the only product.

Ursodeoxycholic acid in pregnancy?

The case of a 34-year-old woman with primary biliary cholangitis (PBC) before, during and after pregnancy is described. The use of ursodeoxycholic acid (UDCA) during and after pregnancy is discussed. UDCA has not been approved by the drug regulatory authorities as a pregnancy-safe drug; therefore, the reluctance of clinicians to prescribe UDCA during pregnancy is understandable. This Grand Round aims to provide a detailed analysis of the current evidence, safety data and clinical experience with UDCA (and alternative drugs) during pregnancy and lactation. Based on this analysis, advice for clinicians regarding the use of UDCA during pregnancy and lactation is given.

NAD+ -Dependent Enzymatic Route for the Epimerization of Hydroxysteroids

Epimerization of cholic and chenodeoxycholic acid (CA and CDCA, respectively) is a notable conversion for the production of ursodeoxycholic acid (UDCA). Two enantiocomplementary hydroxysteroid dehydrogenases (7α- and 7β-HSDHs) can carry out this transformation fully selectively by specific oxidation of the 7α-OH group of the substrate and subsequent reduction of the keto intermediate to the final product (7β-OH). With a view to developing robust and active biocatalysts, novel NADH-active 7β-HSDH species are necessary to enable a solely NAD+ -dependent redox-neutral cascade for UDCA production. A wild-type NADH-dependent 7β-HSDH from Lactobacillus spicheri (Ls7β-HSDH) was identified, recombinantly expressed, purified, and biochemically characterized. Using this novel NAD+ -dependent 7β-HSDH enzyme in combination with 7α-HSDH from Stenotrophomonas maltophilia permitted the biotransformations of CA and CDCA in the presence of catalytic amounts of NAD+ , resulting in high yields (>90 %) of UCA and UDCA.

Review article: therapeutic bile acids and the risks for hepatotoxicity

BACKGROUND

Bile acids play important roles in cholesterol metabolism and signal through farnesoid X receptor and G protein-coupled receptors. Given their importance in liver biology, bile acid therapy enables therapeutic applications beyond the treatment of cholestatic liver disease. However, predicting hepatotoxicity of bile acids in humans is obscured due to inconsistent extrapolations of animal data to humans.

AIM

To review the evidence that could explain discordant bile acids hepatotoxicity observed in humans and animals.

METHOD

Literature search was conducted in PubMed using keywords "bile acid," "transporter," "hepatotoxicity," "clinical study," "animal study," "species difference," "mechanism," "genetic disorder." Relevant articles were selected for review.

RESULTS

Clinically significant hepatotoxicity was reported in response to certain bile acids, namely chenodeoxycholic acid, which was given a boxed warning for potential hepatotoxicity. The chemical structure, specifically the number and orientation of hydroxyl groups, significantly affects their hydrophobicity, an important factor in bile acid toxicity. Experimental studies show that hydrophobic bile acids can lead to liver injury through various mechanisms, such as death receptor signalling, mitochondrial dysfunction and inflammation. Although animal studies play a central role in investigating bile acid safety, there are considerable differences in bile acid composition, metabolism and hepatobiliary disposition across species. This does not allow appropriate safety inference, especially for predicting hepatotoxicity in humans. Exploring evidences stemming from inborn errors, genetic models of disease and toxicology studies further improves an understanding of bile acid hepatotoxicity.

CONCLUSION

Species differences should be considered in the development of bile acid related therapeutics. Although the mechanism of bile acid hepatotoxicity is still not fully understood, continued mechanistic studies will deepen our understanding.

Latest development in the synthesis of ursodeoxycholic acid (UDCA): a critical review

Ursodeoxycholic acid (UDCA) is a pharmaceutical ingredient widely used in clinics. As bile acid it solubilizes cholesterol gallstones and improves the liver function in case of cholestatic diseases. UDCA can be obtained from cholic acid (CA), which is the most abundant and least expensive bile acid available. The now available chemical routes for the obtainment of UDCA yield about 30% of final product. For these syntheses several protection and deprotection steps requiring toxic and dangerous reagents have to be performed, leading to the production of a series of waste products. In many cases the cholic acid itself first needs to be prepared from its taurinated and glycilated derivatives in the bile, thus adding to the complexity and multitude of steps involved of the synthetic process. For these reasons, several studies have been performed towards the development of microbial transformations or chemoenzymatic procedures for the synthesis of UDCA starting from CA or chenodeoxycholic acid (CDCA). This promising approach led several research groups to focus their attention on the development of biotransformations with non-pathogenic, easy-to-manage microorganisms, and their enzymes. In particular, the enzymatic reactions involved are selective hydrolysis, epimerization of the hydroxy functions (by oxidation and subsequent reduction) and the specific hydroxylation and dehydroxylation of suitable positions in the steroid rings. In this minireview, we critically analyze the state of the art of the production of UDCA by several chemical, chemoenzymatic and enzymatic routes reported, highlighting the bottlenecks of each production step. Particular attention is placed on the precursors availability as well as the substrate loading in the process. Potential new routes and recent developments are discussed, in particular on the employment of flow-reactors. The latter technology allows to develop processes with shorter reaction times and lower costs for the chemical and enzymatic reactions involved.

Ductal stones recurrence after extracorporeal shock wave lithotripsy for difficult common bile duct stones: Predictive factors

BACKGROUND & PURPOSE

Extra-corporeal shock wave lithotripsy (ESWL) can be considered in difficult common bile duct stones (DCBDS), with a success rate greater than 90% but data on stone recurrence after ESWL are limited. We performed a retrospective analysis to evaluate long-term outcomes in patients who underwent ESWL for DCBDS.

METHODS

From May 1992 to October 2012, patients who underwent ESWL treatment for DCBDS, not amenable to endoscopic extraction, were included. Data on long-term outcome were collected through phone interviews and medical records.

RESULTS

A total of 201 patients with a successful clearance of DCBDS after ESWL were included. During a median follow-up period of 4.64 years, 40 patients (20%) developed a recurrence of bile duct stones. Logistic regression analysis showed that the common bile duct diameter, gallstones presence and the maximum stone size were significantly associated with recurrence.

CONCLUSIONS

We observed a recurrence rate of 20% over a median follow-up of 4 years. Gallbladder stones, stone size and a dilated common bile duct diameter are risk factors for recurrent stone formation, while ursodeoxycholic acid treatment did not influence recurrence in our population.

Ursodeoxycholic acid for cystic fibrosis-related liver disease

BACKGROUND

Abnormal biliary secretion leads to the thickening of bile and the formation of plugs within the bile ducts; the consequent obstruction and abnormal bile flow ultimately results in the development of cystic fibrosis-related liver disease. This condition peaks in adolescence with up to 20% of adolescents with cystic fibrosis developing chronic liver disease. Early changes in the liver may ultimately result in end-stage liver disease with people needing transplantation. One therapeutic option currently used is ursodeoxycholic acid. This is an update of a previous review.

OBJECTIVES

To analyse evidence that ursodeoxycholic acid improves indices of liver function, reduces the risk of developing chronic liver disease and improves outcomes in general in cystic fibrosis.

SEARCH METHODS

We searched the Cochrane CF and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches, handsearches of relevant journals and abstract books of conference proceedings. We also contacted drug companies and searched online trial registries.Date of the most recent search of the Group's trials register: 09 April 2017.

SELECTION CRITERIA

Randomised controlled trials of the use of ursodeoxycholic acid for at least three months compared with placebo or no additional treatment in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial eligibility and quality. The authors used GRADE to assess the quality of the evidence.

MAIN RESULTS

Twelve trials have been identified, of which four trials involving 137 participants were included; data were only available from three of the trials (118 participants) since one cross-over trial did not report appropriate data. The dose of ursodeoxycholic acid ranged from 10 to 20 mg/kg/day for up to 12 months. The complex design used in two trials meant that data could only be analysed for subsets of participants. There was no significant difference in weight change, mean difference -0.90 kg (95% confidence interval -1.94 to 0.14) based on 30 participants from two trials. Improvement in biliary excretion was reported in only one trial and no significant change after treatment was shown. There were no data available for analysis for long-term outcomes such as death or need for liver transplantation.

AUTHORS' CONCLUSIONS

There are few trials assessing the effectiveness of ursodeoxycholic acid. The quality of the evidence identified ranged from low to very low. There is currently insufficient evidence to justify its routine use in cystic fibrosis.

Beneficial effects of ursodeoxycholic acid via inhibition of airway remodelling, apoptosis of airway epithelial cells, and Th2 immune response in murine model of chronic asthma

BACKGROUND AND AIMS

In previous studies, anti-inflammatory, anti-apoptotic and immunomodulatory effects of ursodeoxycholic acid (UDCA) on liver diseases have been shown. In this study, we aimed to investigate the effects of UDCA on airway remodelling, epithelial apoptosis, and T Helper (Th)-2 derived cytokine levels in a murine model of chronic asthma.

METHODS

Twenty-seven BALB/c mice were divided into five groups; PBS-Control, OVA-Placebo, OVA-50mg/kg UDCA, OVA-150mg/kg UDCA, OVA-Dexamethasone. Mice in groups OVA-50mg/kg UDCA, OVA-150mg/kg UDCA, OVA-Dexamethasone received the UDCA (50mg/kg), UDCA (150mg/kg), and dexamethasone, respectively. Epithelium thickness, sub-epithelial smooth muscle thickness, number of mast and goblet cells of samples isolated from the lung were measured. Immunohistochemical scorings of the lung tissue for matrix metalloproteinase-9 (MMP-9), vascular endothelial growth factor (VEG-F), transforming growth factor-beta (TGF-β), terminal deoxynucleotidyl transferase-mediated dUTP nick endlabeling (TUNEL) and cysteine-dependent aspartate-specific proteases (caspase)-3 were determined. IL-4, IL-5, IL-13, Nitric oxide, ovalbumin-specific immunoglobulin (Ig) E levels were quantified.

RESULTS

The dose of 150mg/kg UDCA treatment led to lower epithelial thickness, sub-epithelial smooth muscle thickness, goblet and mast cell numbers compared to placebo. Except for MMP-9 and TUNEL all immunohistochemical scores were similar in both UDCA treated groups and the placebo. All cytokine levels were significantly lower in group IV compared to the placebo.

CONCLUSIONS

These findings suggested that the dose of 150mg/kg UDCA improved all histopathological changes of airway remodelling and its beneficial effects might be related to modulating Th-2 derived cytokines and the inhibition of apoptosis of airway epithelial cells.

Analytic Reviews : Nonsurgical Alternatives in the Management of Gallstones

Until recently, the only therapeutic option for patients with symptomatic gallstones was surgery. However, sev eral new and innovative nonsurgical approaches are cur rently available, including oral dissolution therapy with the bile salts, ursodeoxycholic and chenodeoxycholic acids, instillation of liquid solvents such as methyl tert- butyl ether directly into the gallbladder or the common bile duct, and extracorporeal shock-wave lithotripsy. We review the role of each of these methods in the management of patients with gallstones as well as the epidemiology, pathogenesis, natural history, and radi ological characteristics of gallstones, all important con siderations when choosing appropriate treatment for the individual patient.

Ursodeoxycholic acid for cystic fibrosis-related liver disease

BACKGROUND

Abnormal biliary secretion leads to the thickening of bile and the formation of plugs within the bile ducts; the consequent obstruction and abnormal bile flow ultimately results in the development of cystic fibrosis-related liver disease. This condition peaks in adolescence with up to 20% of adolescents with cystic fibrosis developing chronic liver disease. Early changes in the liver may ultimately result in end-stage liver disease with people needing transplantation. One therapeutic option currently used is ursodeoxycholic acid.

OBJECTIVES

To analyse evidence that ursodeoxycholic acid improves indices of liver function, reduces the risk of developing chronic liver disease and improves outcomes in general in cystic fibrosis.

SEARCH METHODS

We searched the Cochrane CF and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches, handsearches of relevant journals and abstract books of conference proceedings. We also contacted drug companies.Date of the most recent search of the Group's trials register: 29 May 2014.

SELECTION CRITERIA

Randomised controlled trials of the use of ursodeoxycholic acid for at least three months compared with placebo or no additional treatment in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial eligibility and quality.

MAIN RESULTS

Ten trials have been identified, of which three trials involving 118 participants were included; the dose of ursodeoxycholic acid ranged from 10 to 20 mg/kg/day for up to 12 months. The complex design used in two trials meant that data could only be analysed for subsets of participants. There was no significant difference in weight change, mean difference -0.90 kg (95% confidence interval -1.94 to 0.14) based on 30 participants from two trials. Improvement in biliary excretion was reported in only one trial and no significant change after treatment was shown. There were no data available for analysis for long-term outcomes such as death or need for liver transplantation.

AUTHORS' CONCLUSIONS

There are few trials assessing the effectiveness of ursodeoxycholic acid. There is insufficient evidence to justify its routine use in cystic fibrosis.

Ursodeoxycholic acid for cystic fibrosis-related liver disease

BACKGROUND

Cystic fibrosis-related liver disease peaks in adolescence with up to 20% of people with cystic fibrosis developing chronic liver disease. Early changes in the liver may ultimately result in end-stage liver disease with people needing transplantation. One therapeutic option currently used is ursodeoxycholic acid.

OBJECTIVES

To analyse evidence that ursodeoxycholic acid improves indices of liver function, reduces the risk of developing chronic liver disease and improves outcomes in general in cystic fibrosis.

SEARCH METHODS

We searched the Cochrane CF and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches, handsearches of relevant journals and abstract books of conference proceedings. We also contacted drug companies.Date of the most recent search of the Group's trials register: 10 July 2012.

SELECTION CRITERIA

Randomised controlled trials of the use of ursodeoxycholic acid for at least three months compared with placebo or no additional treatment in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial eligibility and quality.

MAIN RESULTS

Ten trials have been identified, of which three trials involving 118 participants were included. The complex design used in two trials meant that data could only be analysed for subsets of participants. There was no significant difference in weight change, mean difference -0.90 kg (95% confidence interval -1.94 to 0.14) based on 30 participants from two trials. Improvement in biliary excretion was reported in only one trial and no significant change after treatment was shown. Long-term outcomes such as death or need for liver transplantation were not reported.

AUTHORS' CONCLUSIONS

There are few trials assessing the effectiveness of ursodeoxycholic acid. There is insufficient evidence to justify its routine use in cystic fibrosis.

Cholecystectomy: from Langenbuch to natural orifice transluminal endoscopic surgery

Gallstones have led to pain and complications in humankind for millennia. Beginning in the 1880s, cholecystectomy, performed through a sizable abdominal incision, was the treatment of choice for symptomatic cholelithiasis. During the late 1980s pioneering surgeons first used laparoscopic techniques to remove the gallbladder. Although initially associated with a significantly increased rate of bile duct injury, the clinical advantages of laparoscopy compared to open operation became readily apparent, ushering in the "laparoscopic revolution." More recently, attempts at rendering cholecystectomy even less invasive--smaller or fewer incisions or eliminating abdominal incisions altogether--have been described, with limited clinical series reported. At the current time, laparoscopic cholecystectomy is the gold standard for gallbladder removal, and any newer techniques must be demonstrated to result in superior outcomes for widespread adoption.

Preliminary experimental research on the mechanism of liver bile secretion stimulated by peppermint oil

OBJECTIVE

To investigate the choleretic effect and molecular mechanisms of action of peppermint oil (PO), the main component of Danshu capsules (Sichuan Jishengtang Pharmaceutical Co., Ltd., Pengzhou, Sichuan Province, China).

METHODS

Bile secretion was measured by biliary drainage in rats. Total bile acids, total cholesterol and bilirubin in bile were determined. Cholesterol 7α-hydroxylase (CYP7A1), and farnesoid X receptor (FXR) messenger ribonucleic acid (mRNA) levels were assessed in HepG2 cells (a human hepatocellular carcinoma cell line) by reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

PO significantly promoted bile and bile acid secretion in rats. It also increased bile acid efflux and decreased cholesterol levels (P < 0.01) in bile. In HepG2 cells the mRNA levels of CYP7A1 and FXR were significantly upregulated after treatment with PO.

CONCLUSIONS

PO stimulates bile fluid secretion and thus has a choleretic effect. PO might play a role in upregulating CYP7A1 and FXR mRNA levels, suggesting that the molecular mechanisms are related to gene expression involved in bile acid synthesis.

Chemoprevention of colorectal cancer: a role for ursodeoxycholic acid, folate and hormone replacement treatment?

Chemoprevention of colorectal cancer has been an intense focus of research for many years. Among the possible candidate agents, ursodeoxycholic acid, folate, and hormone replacement therapy have been recently investigated with conflicting data. Experimental evidence shows that UDCA, folate and HRT target critical molecular events important for colon carcinogenesis. In animal models of sporadic, familial and inflammatory-associated cancers, they have shown to reduce colonic neoplasms. Observational studies have shown compelling evidence of possible protective effects of all three agents. However, randomised-controlled studies have yielded disappointing results, raising the issues of possible harm rather than protective effect for some of them. In this review experimental and clinical data on UDCA, folate and HRT as potential chemopreventive agents are discussed.

Novel bile acids from bear bile powder and bile of geese

Two new bile acids, tauroselocholic acid (1) and tauroansocholic acid (2), a new natural bile acid, cygnocholic acid (3) were respectively isolated from bear bile powder Selenaretos thibetanus CUVIER and bile of geese Anser anser domesticus, together with seven known compounds. By spectrum analysis of MS, 1D and 2D NMR, the structures of the new compounds were elucidated as 3alpha,7alpha,9alpha-trihydroxy-5beta-cholan-24-oic acid N-[2-sulfoethyl] amide (1), 3alpha,5,7alpha-trihydroxy-5beta-cholan-24-oic acid N-[2-sulfoethyl] amide (2) and 3alpha,7alpha,15alpha-trihydroxy-5beta-cholan-24-oic acid (3).

Ursodeoxycholic acid improves gastrointestinal motility defects in gallstone patients

AIM: To simultaneously evaluate the presence of defects in gallbladder and gastric emptying, as well as in intestinal transit in gallstone patients (GS) and the effect of chronic ursodeoxycholic acid (UDCA) administration on these parameters and on serum bile acids and clinical outcome in GS and controls (CTR).

METHODS: After a standard liquid test meal, gallbla-dder and gastric emptying (by ultrasound), oroileal transit time (OITT) (by an immunoenzymatic technique) and serum bile acids (by HPLC) were evaluated before and after 3 mo of UDCA (12 mg/kg bw/d) or placebo administration in 10 symptomatic GS and 10 matched healthy CTR.

RESULTS: OITT was longer in GS than in CTR (P < 0.0001); UDCA significantly reduced OITT in GS (P < 0.0001), but not in CTR. GS had longer gastric half-emptying time (t_1/2) than CTR (P < 0.0044) at baseline; after UDCA, t_1/2 significantly decreased (P < 0.006) in GS but not in CTR. Placebo administration had no effect on gastric emptying and intestinal transit in both GS and CTR.

CONCLUSION: The gallstone patient has simultaneous multiple impairments of gallbladder and gastric emptying, as well as of intestinal transit. UDCA administration restores these defects in GS, without any effect in CTR. These results confirm the pathogenetic role of gastrointestinal motility in gallstone disease and suggest an additional mechanism of action for UDCA in reducing bile cholesterol supersaturation.

Gallstone disease. Management of common bile-duct stones and associated gallbladder stones: Surgical aspects

For many years, open exploration of the common bile duct has been the treatment of choice for patients with common bile-duct stones. During recent decades endoscopic sphincterotomy has gained wide acceptance as an effective and less invasive alternative. After sphincterotomy, subsequent (laparoscopic) cholecystectomy is warranted in patients with gallbladder stones. This chapter will discuss whether sphincterotomy should be performed prior to, during or after cholecystectomy, and will also address the question of whether single-stage treatment by laparoscopic cholecystectomy and laparoscopic bile-duct exploration is in fact preferable. The rate of recurrent choledocholithiasis after endoscopic biliary sphincterotomy can reach more than 20%. This review focuses on the risk factors--delayed bile-duct clearance and bactobilia--that may lead to recurrent primary bile-duct stone formation. Underlying altered bile composition (relative phospholipid deficiency) should be recognised in a subgroup of patients. Identification of these risk factors may significantly affect treatment policy.

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.

Ursodeoxycholic acid for cystic fibrosis-related liver disease

BACKGROUND

Cystic fibrosis-related liver disease peaks in adolescence with up to 20% of patients developing chronic liver disease. Early changes in the liver may ultimately result in end stage liver disease with patients needing transplantation. One therapeutic option currently used is ursodeoxycholic acid.

OBJECTIVES

To assess the effectiveness of ursodeoxycholic acid in cystic fibrosis liver disease.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group trials register, and contacted drug companies. Date of the most recent search of the Group's specialised register: June 1999.

SELECTION CRITERIA

Randomised and quasi-randomised trials of use of ursodeoxycholic acid for at least three months compared with placebo or no additional treatment in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial eligibility and quality.

MAIN RESULTS

Three trials involving 118 patients were included. The complex study design used in two trials meant that data could only be analysed for subsets of patients. There was no difference in weight change (weighted mean difference -0.496, 95% confidence interval -1.545 to +0.553) based on 30 patients from two trials. Improvement in biliary excretion was reported in only one study and no significant change after treatment was shown. Long term outcomes such as death or need for liver transplantation were not reported.

REVIEWER'S CONCLUSIONS

There are few trials assessing the effectiveness of ursodeoxycholic acid. There is insufficient evidence to justify is its routine use in cystic fibrosis.

Long-term ursodeoxycholic acid therapy is associated with reduced risk of biliary pain and acute cholecystitis in patients with gallbladder stones: a cohort analysis

Whether ursodeoxycholic acid (UDCA) therapy alters the long-term clinical course of gallstones (GS) without stone dissolution remains unknown. We aimed to clarify the relationship between long-term UDCA therapy and risks of biliary pain or acute cholecystitis in GS patients. We also aimed to identify factors affecting the natural course, and to explore a simple patient selection criteria for UDCA therapy. A cohort of 527 uncomplicated GS patients with or without UDCA (600 mg/d) followed for up to 18 years was analyzed. Patients who had frequent attacks or were complicated with cholecystitis were converted to cholecystectomy. History and UDCA therapy were identified on Cox analysis as 2 factors affecting the long-term clinical course. In patients without therapy, history was the only predictor of biliary pain among various patient or stone characteristics; biliary pain was rare in asymptomatic patients, while frequent in symptomatic patients (P <.001). UDCA therapy was associated with reduced risk for biliary pain in both symptomatic (62% vs. 92% in untreated patients at 10 years; P <.001; relative risk, 0.19; 95% CI, 0.10-0.34) and asymptomatic patients (6% vs. 12% in untreated patients at 10 years; P =.037; relative risk, 0.19; 95% CI, 0.04-0.91). Risk for the conversion was also reduced in UDCA-treated symptomatic patients (26% vs. 88% in untreated patients at 10 years, P <.001; relative risk, 0.08; 95% CI, 0.03-0.22). These effects were independent of stone dissolution. Three factors were identified on Cox analysis as affecting GS dissolution: radiolucency, small size (<10 mm) of stones, and visualized gallbladder (GB) on cholecystogram. A selection criteria based on these appears to exhibit high sensitivity (74%) and specificity (95%) for dissolution. UDCA therapy might be considered in symptomatic patients fulfilling these criteria, and also in patients who have significant surgical risk, because the longterm therapy is clearly associated with reduced risk of biliary pain and acute cholecystitis.

Bile acid kinetics in man studied by radio thin-layer chromatography and densitometry coupling

A method based on coupling of the techniques of radioscanning a TLC plate and densitometry has been developed for the determination of pool sizes and fractional turnover rate of bile acids in man after intraduodenal administration of 14C-labelled acid. The validity of the method has been checked by comparison of the results obtained with those of an enzymatic spectrophotometric analysis, and a measurement of the radioactivity by liquid scintillation counting, after elution of the separated bile acid from a TLC plate. Advantages of the proposed method over the previous one include a reduced number of manipulations, the possibility of automation, a better reproducibility, and the possibility of elaborating the radiometric data obtained for the primary bile acid for better characterising its metabolism inside the enterohepatic circulation.

The indirect UV detection in the analysis of ursodeoxycholic acid and related compounds by HPCE

A high-performance capillary zone electrophoretic (HPCE) assay has been developed for the determination of ursodeoxycholic acid (UDCA) and its usual impurities. Considering the low molecular absorptivity of UDCA and its related compounds indirect UV detection was used. The electrophoretic capillary was filled with a background electrolyte (BGE) containing an UV absorbing ion: benzoic acid (BA) or 5,5-diethylbarbituric acid (DBA). To enhance the selectivity of the assay diimethyl-beta-cyclodextrines (D-beta-CDs) or trimethyl-beta-cyclodextrines (T-beta-CDs) have been added to the running buffer together with methylcellulose or urea. All considered impurities were well resolved with two buffers studied, with the exception of methylursodehoxycholate, a neutral compound.

Relationship between structure and intestinal absorption of bile acids with a steroid or side-chain modification

A structure-activity relationship for bile acid (BA) intestinal absorption is known to exist. To better understand the BA structural requirements for optimal BA intestinal absorption, rabbit ileal perfusion studies were performed. Unconjugated BA: Ursodeoxycholic (UDCA) and ursocholic acid (UCA) with methyl (6MUDCA and 6MUCA) or fluoro group (6FUDCA and 6FUCA) in the 6 position and UCA with a methyl group in 23 position (23MUCA) were compared with unconjugated UDCA, UCA, deoxycholic (DCA), chenodeoxycholic (CDCA), hyocholic (HCA), and hyodeoxycholic (HDCA) acid. BA lipophilicity was evaluated by their octanol-water partition coefficient. Conjugated BA: Taurine-conjugated UDCA and UCA with a methyl group in the 23 position (T23MUDCA and T23MUCA) were compared with the corresponding taurine-conjugated natural analogs. An analog of glycine-conjugated UDCA with the C24 amide bond replaced by a -CO-CH2- in the 24 position (24PUDCA) was studied and results were compared with the natural form (GUDCA). Unconjugated BA absorption was dose dependent (i.e., passive) and followed their lipophilicity: DCA > 6MUDCA > CDCA > HDCA > UDCA > HCA > 6FUDCA > 6MUCA > 6FUCA > UCA. Conjugated BA absorption was active, and Vmax was in the following order: TCA > TUDCA > TUCA > T23MUCA > T23MUDCA > 24PUDCA > GUDCA. 24PUDCA transport was also active and higher than GUDCA.

CONCLUSION

Passive transport is dependent on BA lipophilicity. Conjugated BAs are actively transported, and the presence of a 23-C methyl group does not improve transport when compared with the natural analogs. The substitution of the C24 amide bond with a -CO-CH2-still affords interaction of the BA with the intestinal transport carrier.

Synthesis and physicochemical, biological, and pharmacological properties of new bile acids amidated with cyclic amino acids

New analogs of cyclic amino acid-conjugated bile acids were synthesized, and their physicochemical and biological properties were compared with those of natural analogs. Ursodeoxycholic acid was amidated with D-proline, L-proline, 4-hydroxy-L-proline, and 4-methoxy-L-proline. Hyocholic and hyodeoxycholic acids were amidated with L-proline. The physicochemical properties were similar to those of the natural analogs. All of them were highly stable toward enzymatic C-24 amide bond hydrolysis and 7-dehydroxylation. Their transport, metabolism, and effect on biliary lipid secretion were evaluated in bile fistula rat after intravenous infusion. All the analogs were secreted in bile unmodified. The 4-methoxy-L-proline derivative produced the highest secretion rate, much higher than those of all the other natural and synthetic analogs. This was associated with a selective reduction of cholesterol secretion with normal phospholipid secretion and choleresis. When coinfused, all the analogs were able to prevent the hepatotoxicity induced by intravenous taurochenodeoxycholic acid, as revealed by normal choleresis, alkaline phosphatase, and lactate dehydrogenase values in bile. Considering the overall data, 4-methoxy-L-proline, 4-hydroxy-L-proline, and L-proline derivatives of ursodeoxycholic acid were more potent than the natural analogs.

What should I do about my patient's gall stones?

The problem of benign biliary disease is one that causes significant morbidity and social economic strain in the western world. The classical treatment, cholecystectomy, has been challenged by various medical and surgical techniques in a seemingly random nature. The development of the treatment of gall stone disease is reviewed by analysis of published studies over the last 20 years. The advantages and disadvantages are discussed as an overview and summary of the current management of gall stone disease in the light of our knowledge of its malignant potential.

Continuous spectrophotometric assay of conjugated bile acid hydrolase

Conjugated bile acid hydrolase (CBAH) refers to a class of enzymes which catalyze the cleavage of the amino acid moieties from conjugated bile acids. These enzymes are significant because of their role in providing substrates for further microbial metabolism in the gastrointestinal tract. They also are used in research laboratories for the deconjugation of bile acids prior to structural analyses. A continuous spectrophotometric assay for CBAH activity was developed using a conjugate of cholic acid and the chromophore, 5-amino-2-nitro-benzoic acid. The free chromophore is detected by virtue of its absorbance at 410 nm. The CBAH from Clostridium perfringens displayed a Km for this substrate of 120 microM. These results demonstrate that this new compound functions as an effective substrate of the enzyme and forms the basis for a convenient and rapid method to monitor CBAH activity.

Experimental evaluation of a model for predicting micellar composition and concentration of monomeric species in bile salt binary mixtures

The critical micellar concentration (cmc) values of some mixed systems containing two bile salts were determined by a maximum pressure bubble method and compared with those derived from a theoretical model developed for nonionic surfactants to assess the applicability of this model to such systems. Some assumptions on which the presumed validity of this model was based are discussed. The following binary mixtures were investigated: sodium chenodeoxycholate with cholate, ursocholate and ursodeoxycholate, either unconjugated or conjugated with taurine and glycine at different mole fractions (0, 0.25, 0.5, 0.75, 1) in 0.15 M NaCl. For these mixtures, experimentally determined data were in good agreement with values predicted by the theoretical model: both the cmc and the surface tension at this concentration of the mixtures were intermediate between those of the two pure bile salts; also, as the total bile salt concentration increased, the mixed micelles became enriched with the bile salt having the highest cmc, whereas the total monomer activity, determined by a potentiometric method employing a bile salt-selective electrode, increased only slightly. To test this model in an in vitro system, surface tension was also measured in ox bile samples that were enriched by 50% with sodium ursodeoxycholate, chenodeoxycholate, or their taurine amidates. The cmc and the surface tension at this concentration of the artificial bile increased when enriched with a bile salt with a cmc higher than that of endogenous salts (e.g. ursodeoxycholate versus taurocholate), whereas the reverse occurred for mixtures enriched with a bile salt with a lower cmc, such as chenodeoxycholate.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolism, pharmacokinetics, and activity of a new 6-fluoro analogue of ursodeoxycholic acid in rats and hamsters

BACKGROUND/AIMS

The effectiveness of ursodeoxycholic acid in treating biliary liver diseases is limited by low bioavailability and moderate activity. A new analogue of ursodeoxycholic acid was synthesized with a fluorine atom in position 6 because this should have resulted in an analogue more hydrophilic than ursodeoxycholic acid but with similar detergency.

METHODS

After synthesis, detergency, solubility, and lipophilicity of the 6-fluoro analogue in aqueous solution were determined and compared with those of natural analogues. Stability toward 7-dehydroxylation was assessed in human stools, pharmacokinetics and metabolism were evaluated in bile fistula rats and hamsters, accumulation in bile with long-term feeding was assessed in the hamsters, and the ability to prevent the hepatotoxic effects of taurochenodeoxycholic acid was evaluated in bile fistula rats after intraduodenal coinfusion.

RESULTS

6-Fluoro-ursodeoxycholic acid was more stable than its parent molecule toward 7-dehydroxylation, it was efficiently secreted in bile, and its total recovery was very high. With long-term administration of 6-fluoro-ursodeoxycholic acid, taurine and glycine amidates accounted for more than 60% of the total biliary bile acids (15% ursodeoxycholic acid). The 6-fluoro analogue prevented the hepatotoxic effects of taurochenodeoxycholic acid.

CONCLUSIONS

The results suggest that 6-fluoro-ursodeoxycholic acid has considerable potential as a pharmaceutical agent in the treatment of cholestatic liver disease.

Bioavailability study of a new, sinking, enteric-coated ursodeoxycholic acid formulation

A new enteric-coated ursodeoxycholic acid (UDCA) formulation which sinks in the stomach and releases the drug only at a pH > or = 6.5 was developed. In 12 healthy subjects we measured, using a specific enzyme immunoassay, the serum levels of UDCA after a single oral dose of 450 mg of UDCA in three different formulations; enteric coated sinking tablet, stomach-floating enteric coated hard gelatin capsule and conventional gelatin capsule. The drug was given after a meal. Results are expressed as mean +/- SD. The area under the curve [AUC, mumol l-1 (8 h)] following oral administration of enteric-coated, sinking UDCA (39.0 +/- 8.5) was significantly higher than that obtained after both conventional UDCA (30.5 +/- 4.9) and floating enteric coated UDCA (29.3 +/- 3.4). Moreover, the maximum UDCA serum concentration (Cmax) was significantly higher with the enteric coated sinking UDCA formulation when compared to the other two formulations, while the time of maximum UDCA serum concentration (tmax) occurred later. These results may be explained by the hypothesis that the sinking tablet is expelled in the latter phase of gastric emptying along with the solid content. It therefore reaches the intestine at the highest alkalization phase caused by sustained biliary and pancreatic secretions. When released, the protonated insoluble UDCA is promptly solubilized by the alkaline pH thus giving a higher UDCA concentration gradient which facilitates its passive absorption. On the other hand, the floating capsule reaches the intestine too early, still in presence of an acidic pH; and in this condition UDCA is almost insoluble and consequently may be malabsorbed.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatic uptake and intestinal absorption of bile acids in the rabbit

The existence of transporters for bile acids (BA) in liver and intestine has been well documented, but information is still needed as to their respective transport capacity. In the present investigation, we compared the hepatic and intestinal transport rates for BA, using perfused livers and intestines. The livers and intestines were separately perfused and dose-response curves (0.25-10 mM) for tauroursodeoxycholate, taurocholate and taurodeoxycholate were obtained. The intestinal and mesenteric concentration and bile acid pattern were also evaluated in six non-fasting rabbits. Taurocholic, tauroursodeoxycholic and taurodeoxycholic acid ileal absorption showed saturation kinetics in the intestine as in the liver; the maximal uptake velocity for each bile acid in the liver was tenfold higher than the respective maximal transport velocity in the intestine; the Km values obtained in the liver were of the same order of magnitude, i.e. in the millimolar range. Taurocholic, tauroursodeoxycholic and taurodeoxycholic acid transport differences in the liver paralleled those in the intestine. Although the intestine was not homogeneously filled, the bile acid concentration in the ileal content fell into the range of the Km for the three studied bile acids, while the portal blood total bile acid concentration was inferior to the observed Kms of liver uptake. Therefore, both the hepatic and intestinal systems do not operate at their maximal transport rates at the prevailing concentrations in portal blood and luminal content, and the hepatic transport occurs at its highest efficiency (below the Km values) in physiological conditions.

Pharmacological treatment of gallstones. Practical guidelines

Laparoscopic cholecystectomy is the treatment of choice for symptomatic cholelithiasis. Medical treatment is indicated for patients who are not fit or are afraid of surgery. For any form of medical treatment to be effective gallstones must be cholesterol rich, thus radiolucent, and the cystic duct must be patent, as indicated by gallbladder opacification on oral cholecystography. Three forms of medical treatment are currently available for clinical use--oral bile acids, bile acids as adjuncts to lithotripsy and contact dissolution using methyltertbutylether. The choice of treatment depends mainly on gallstone size. Gallstones < 6 mm in diameter are best treated with oral bile acids, chenodeoxycholic acid 15 mg/kg/day or ursodeoxycholic acid 10 mg/kg/day given alone or in combination (5 mg/kg/day each). Careful patient selection and bedtime administration of the whole daily bile acid dose enhance treatment, and may achieve up to 75% complete dissolution annually. Single stones < 30 mm in diameter or multiple stones (n < 3) are best treated with lithotripsy combined with oral bile acid for dissolution of fragments. Annual dissolution rates are about 80 and 40% for single and multiple stones, respectively. Stones of any size and number can be dissolved by direct contact dissolution using methyltertbutylether. Dissolution has been reported to be complete in almost 100% of stones, but debris is frequently left behind in the gallbladder. Following dissolution using any form of treatment, gallstones recur in about 50% of patients, and cannot be reliably prevented by low dose bile acid or dietary manipulations. Failing prevention, early detection and retreatment of recurrent stones is the best alternative option as a long term strategy.

Duodenal bile examination in identifying potential non-responders to bile salt treatment and its comparison with gall bladder bile examination

The results of bile salt treatment in patients with radiolucent stones and a functioning gall bladder have been poor. In 42 of these patients awaiting cholecystectomy we determined the value of duodenal bile examination in predicting gall stone composition, and thus identifying those less likely to respond to bile salt therapy. Based on chemical analysis and scanning electron microscopy, 28 of 42 (67%) gall stones retrieved at surgery were potentially insoluble. Microscopic examination of duodenal bile correctly identified 21 (75%) of them: it predicted all four (100%) pigment stones, three of six (50%) calcium carbonate containing cholesterol stones, and 14 of 18 (78%) cholesterol stones with pigment shells. It was nearly as reliable as microscopic examination of bile aspirated directly from the gall bladder during surgery (21 (75%) v 23 (82%); p = NS). Furthermore, the presence of cholesterol crystals in duodenal bile was a more sensitive indicator than chemical detection of supersaturation (34 of 38 (89%) v 25 of 35 (71%); p < 0.05) for prediction of cholesterol gall stones. Microscopic examination of duodenal bile, if used as a screening test, could help to exclude potential non-responders and thereby improve considerably the results of oral bile salt treatment for gall stone dissolution.

Gallstone recurrence after shock-wave therapy

BACKGROUND/AIMS

The long-term outcome of nonoperative gallstone therapy depends on both absence of stones and absence of biliary pain. The aim of the present study was to determine the rate of stone recurrence and the rate of symptoms within 5 years after successful shock wave lithotripsy combined with bile acid therapy.

METHODS

One hundred consecutive patients (single stones, n = 89; 2 or 3 stones, n = 11) were followed up for a median of 4.3 years after stone disappearance and discontinuation of bile acids.

RESULTS

Twenty-three of the 100 patients developed recurrent stones. Calculated by actuarial analysis, the recurrence rate was 7% +/- 3%, 11% +/- 3%, 13% +/- 4%, 20% +/- 5%, and 31% +/- 7% (mean +/- SD) at 1, 2, 3, 4, and 5 years, respectively. The recurrent stones were small (6 +/- 5 mm) and were associated with recurrent biliary pain in 14 (61%) of the 23 patients. Repeated shock wave lithotripsy and/or bile acid medication resulted in stone disappearance in only 10 of 20 patients with recurrence.

CONCLUSIONS

The long-term rate of stone recurrence after lithotripsy of primarily solitary gallbladder calculi is lower than expected from post-bile acid dissolution trials. Recurrence of stones frequently is associated with recurrence of biliary pain.

Influence of ursodeoxycholic acid on biliary lipids

The advent of bile acid therapy has shed some light on the mechanisms involved in determining bile lipid secretion. The administration of cholelytic bile acids results in a lowering of cholesterol percent molar and saturation index due to a reduction in cholesterol secretion. Studies carried out after administration of bile acids showed initially that biliary cholesterol secretion rates were dependent on the hydrophobic/hydrophilic balance of the prevailing bile acid present in bile. However, more detailed investigations showed that some bile acids (cholic and chenodeoxycholic acids) did not follow this rule because of the presence of other mechanisms involved in determining biliary cholesterol secretion and a possible link between cholesterol synthesis and biliary cholesterol secretion. Several different human models have been used in more recent studies to arrive at a better understanding of the mechanisms involved in determining bile lipid secretion: obese patients, obese patients in rapid weight loss, patients with non-familial hypercholesterolemia and primary biliary cirrhosis. The findings in these studies indicate how modifications in biliary lipid secretion can easily be induced when there are changes in the relative amounts of bile acids. These changes may bring about modifications in intestinal absorption, liver synthesis, and secretion of cholesterol and bile acids that could possibly lead to the formation of lithogenic bile and subsequently to cholesterol gallstones.

HPLC-fluorescence determination of bile acids in pharmaceuticals and bile after derivatization with 2-bromoacetyl-6-methoxynaphthalene

2-Bromoacetyl-6-methoxynaphthalene was used as a pre-chromatographic fluorescent labelling reagent for the high-performance liquid chromatographic (HPLC) analysis of bile acids. The derivatization reaction was performed in an aqueous medium in the presence of tetrahexylammonium bromide by ultrasonication at 40 degrees C to give fluorescent esters which were separated by reversed-phase HPLC and detected fluorimetrically (lambda ex = 300 nm, lambda em = 460 nm). Applications to the determination of ursodeoxycholic acid (UDCA) and chenodeoxycholic acid (CDCA) in their pharmaceutical formulations are described. The method was also applied to the determination of free and conjugated bile acids in human bile samples.

HPLC study of the impurities present in different ursodeoxycholic acid preparations: comparative evaluation of four detectors

The use of HPLC with different detectors has been investigated for the analysis of bile acid impurities present in four different commercially available ursodeoxycholic acid preparations. The bile acids were efficiently separated by C18 reversed-phase HPLC using methanol-water (3:2, v/v) as the mobile phase. The detectors used for bile acid detection were: UV at 200 nm refractive index (RI) and an evaporative light scattering mass detector (ELSD II). A prederivatization method with the formation of a fluorescent naphthacyl ester has also been used. GC-MS analysis of Me-TMS bile acid derivatives was included as a reference method. The four ursodeoxycholic acid samples were 98-99% pure. The main impurities present in the samples were chenodeoxycholic acid and to a lesser extent lithocholic acid. Only one sample was found to be almost 100% pure using all the detectors. Significant agreement of the data was found between RI, ELSD II detectors and the fluorescent method; the UV detector was unsuitable for use in this method. The analytical performances of the four detectors for bile acid analysis are reported and discussed. When the four-detector data were compared with the GC-MS method, reasonable agreement resulted. Discordant results were found in the quantitation of trace impurities like lithocholic acid and/or other minor bile acids present in amounts less than 0.1%.

Ursodeoxycholic acid administration on bile acid metabolism in patients with early stages of primary biliary cirrhosis

Ursodeoxycholic acid has been proposed for the treatment of primary biliary cirrhosis. The aim of this study was to evaluate the effect of ursodeoxycholic acid administration on bile acid metabolism in patients with early-stage primary biliary cirrhosis. Biliary bile acid composition, primary bile acid pool sizes, synthesis, and fractional turnover rate were measured before and after four weeks of ursodeoxycholic acid administration (600 mg/day) in nine patients with biopsy-proven primary biliary cirrhosis (stages I-III). Molar percentages of chenodeoxycholic, cholic, and deoxycholic acids in bile were significantly decreased by ursodeoxycholic acid administration, while its biliary concentration increased to 34.2% at the end of the same four-week period. The cholic and chenodeoxycholic acid pools decreased, although not significantly, while the deoxycholic acid pool was reduced by 60% (from 0.7 +/- 0.12 to 0.29 +/- 0.07 mmol, P < 0.002). Primary bile acid synthesis was slightly increased, and fractional turnover rate was significantly increased. The conversion rate of cholic to deoxycholic acid was measured and found to be significantly increased (P < 0.05) after ursodeoxycholic acid administration; however, serum levels of both free and conjugated deoxycholic acid were significantly decreased (from 23.2 +/- 9.7 to 3.8 +/- 1.9 mumol/liter, P < 0.001). We conclude that in patients with primary biliary cirrhosis, ursodeoxycholic acid administration replaces endogenous bile acids in the enterohepatic circulation by increasing bile acid fractional turnover rate without significant increments of their hepatic synthesis.

Oral and contact dissolution of gallstones

The appropriate selection of patients for treatment with oral ursodeoxycholic acid (UDCA)--a drug that has virtually no side effects--results in about 50% of patients experiencing safe dissolution of gallstones within 2 years. Eligible patients have small (less than 20 mm in diameter) radiolucent gallstones in a gallbladder visualized by oral cholecystography (OCG); ideal candidates are thin women who have gallstones that are less than 15 mm in diameter, floating when observed by OCG, or of low density on computed tomographic (CT) scanning. Contact dissolution with methyl tert-butyl ether (MTBE) is rapid, effective more often than UDCA, and safe but requires the expertise of an interventional radiologist. Any size and number of cholesterol gallstones that are not CT-dense will be dissolved by MTBE, leaving at most only insoluble debris that is clinically innocuous. Although gallstones recur after dissolution by UDCA or MTBE in 50% of patients within 5 years, recurrent gallstones are usually asymptomatic and/or can probably be dissolved. We conclude that oral or contact dissolution provides an alternative treatment to cholecystectomy for about 30% of patients with symptomatic gallstones.

Efficacy of bile acid therapy for gallstone dissolution: a meta-analysis of randomized trials

To define better the efficacy of bile acid therapy for dissolution of radiolucent gallstones, we performed a meta-analysis of published trials from January 1966 to September 1992. Studies were identified using a MEDLINE computer search followed by an extensive manual search. The inclusion criteria used were: randomized trial, radiolucent gallstones in a visualizing gallbladder on oral cholecystography, and complete stone dissolution confirmed by oral cholecystography or ultrasound. Study results were pooled into 6 groups: placebo: high- and low-dose chenodeoxycholic acid (CDCA) (> or = 10 mg.kg/day and < 10 mg.kg/day); high- and low-dose ursodeoxycholic acid (UDCA) (> or = 7 mg.kg/day and < 7 mg.kg/day) and combined CDCA plus UDCA. Homogeneity calculations were performed and the percentage of complete stone dissolution calculated for each group with 95% confidence intervals. Of 66 trials identified, 23 comprising 1949 patients met the inclusion criteria. A total of 1062 patients were treated with CDCA, 819 with UDCA and 78 combination therapy. In studies > 6 months' duration, high-dose UDCA completely dissolved stones in 37.3% of patients (95% C.I. 33-42%), low-dose UDCA in 20.6%) and high-dose CDCA 18.2% (95% C.I. 15-21%). Based on only two studies, combination therapy achieved dissolution in 62.8% (95% C.I. 51-74%) of patients. Stones less than 10 mm dissolved significantly more frequently than stones larger than 10 mm. This analysis shows that UDCA in doses greater than 7 mg.kg/day taken for greater than 6 months will dissolve radiolucent gallstones in 38% of patients. The combination of UDCA and CDCA may be more efficacious but this observation is based upon only 78 patients and requires confirmation in further randomized trials.

Clinical, ultrasonographic, and roentgenographic study in 134 asymptomatic gallstone carriers. Is oral ursodeoxycholic acid treatment worthwhile?

We investigated retrospectively the ultrasonographic and roentgenographic characteristics of the gallstones and the gallbladder in 134 symptom-free carriers and evaluated prospectively the outcome and side effects of 6 to 24 months' ursodeoxycholic acid (UDCA) therapy in 36 individuals with silent stones. Two-thirds of the 134 subjects had multiple stones, and 71-75% had stones less than 15 mm in diameter. Gallstone calcification was detected in 13%. A non-functioning gallbladder was observed in 19%, whereas gallbladder contraction was normal in 64 of 76 gallstone carriers. With regard to oral bile acid treatment, complete and partial dissolutions were achieved in 7 and 9 of 33 subjects, respectively (48.5%). Development of a non-functioning gallbladder occurred in 9%, and acquired gallstone calcification was seen in another 15%. We conclude that: i) the characteristics of the gallstones and the gallbladder are similar to those observed in symptomatic patients, and ii) UDCA therapy may be given in selected symptom-free carriers for no more than 6-12 months. Thereafter, it does not appear to be cost-effective.