Bioequivalence and Pharmacokinetic Profiles of Generic and Branded Obeticholic Acid in Healthy Chinese Subjects Under Fasting and Fed Conditions.

OBJECTIVES: This study was conducted to evaluate the bioequivalence (BE) of a generic form of obeticholic acid (OCA) and OcalivaTM under fasting and fed conditions and to determine the effects of food on the pharmacokinetic (PK) profiles of OCA in healthy Chinese subjects. METHODS: A randomized, single-dose, three-sequence, three-period, partial replicated crossover study was conducted with a 21-day washout interval between periods under fasting (n=48) and fed (n=48) conditions. Blood samples for OCA and its metabolites Glyco-OCA and Tauro-OCA were collected up to 168 hours after administration in each period. PK parameters were calculated using the non-compartmental method. Geometric mean ratios for PK parameters of the test to reference drug under fasting and fed conditions and their 90% confidence intervals were estimated. Safety evaluations were carried out all through the study. RESULTS: A total of 91 subjects completed the study with 45 in a fasted state and 46 receiving a high-fat diet. There were no serious or unexpected drug-related adverse events occurring during the study. There was no significant difference in the main PK parameters of the two preparations, irrespective of the fasting or fed conditions. Under fasting and fed conditions, the SWR of lnCmax, lnAUC0-t and lnAUC0-∞ were 0.445, 0.370, 0.448, 0.340, 0.168, and 0.180, respectively. Thus, the average BE or the reference-scaled average BE was used to verify that the two preparations were bioequivalent under fasting and fed conditions. Compared with the fasting state, the AUC0-t of the test drug, the AUC0-t, and AUC0-∞ of the reference drug were higher in the fed state. CONCLUSION: The test drug and the reference drug were BE and well tolerated in Chinese healthy subjects under both fasting and fed conditions. Food-intake may cause a significant difference in the main PK parameters of the two preparations.

Comparison of the Pharmacokinetics of Generic Versus Branded Obeticholic Acid in a Chinese Population: Effects of Food and Sex.

The present study assessed the pharmacokinetics and bioequivalence of a single 10-mg dose of a generic and the branded formulation (Ocaliva) of obeticholic acid (OCA) in healthy Chinese subjects under fasting and fed conditions. The possible effects of food and sex on the pharmacokinetics of OCA and its 2 active metabolites (glyco-OCA and tauro-OCA) were evaluated. Plasma concentrations of OCA and its 2 active metabolites were measured by liquid chromatography-tandem mass spectrometry. The 90%CIs of the ratios of the test and reference formulations for Cmax , AUC0-t , and AUC0-∞ of OCA, glyco-OCA, and tauro-OCA were contained entirely within the 80% to 125% range required for bioequivalence under fasting and fed conditions. Plasma exposure of OCA was 30% to 36% higher under fed compared with fasting conditions. Plasma exposure of OCA, glyco-OCA, and tauro-OCA was 39% to 66%, 22% to 58%, and 37% to 84% higher, respectively, in women compared with men under fasting and fed conditions. In conclusion, OCA was well tolerated in healthy Chinese subjects under fasting and fed conditions. The single 10-mg dose of a generic OCA formulation was bioequivalent to Ocaliva. Food and sex impacted the pharmacokinetics of OCA and/or its 2 active metabolites. Further studies are required to determine if these effects are clinically relevant.

A novel LC-MS/MS method for simultaneous estimation of obeticholic acid, glyco-obeticholic acid, tauro-obeticholic acid in human plasma and its application to a pharmacokinetic study.

A rapid, robust, simple, selective, and sensitive liquid chromatography-tandem mass spectrometry method was developed for the simultaneous estimation of obeticholic acid and its two pharmacologically active metabolites, glyco-obeticholic acid, and tauro-obeticholic acid in human plasma. The analytes and their heavy stable isotope-labeled internal standards were extracted from 250 µL human plasma by a solid-phase extraction technique. The method linearity was established over a concentration range of 0.410 to 120.466 ng/mL for obeticholic acid, 0.414 to 121.708 ng/mL for glyco-obeticholic acid, and 0.255 to 75.101 ng/mL for tauro-obeticholic acid. The method was fully validated as per current guidelines on bioanalytical method validation of "United States of Food and Drug Administration" and "European Medicines Agency." The method was successfully applied to study the pharmacokinetics of obeticholic acid, glyco-obeticholic acid, and tauro-obeticholic acid following oral administration of obeticholic acid tablets to healthy male volunteers. All the measured concentrations were within calibration curve ranges.

Obeticholic acid improves hepatic bile acid excretion in patients with primary biliary cholangitis.

BACKGROUND & AIMS: Obeticholic acid (OCA) is an agonist of the nuclear bile acid receptor farnesoid X receptor, which regulates hepatic bile acid metabolism. We tested whether OCA treatment would influence hepatic transport of conjugated bile acids in patients with primary biliary cholangitis (PBC) who responded inadequately to treatment with ursodeoxycholic acid (UDCA). METHODS: Eight UDCA-treated patients with PBC with alkaline phosphatase ≥1.5 times the upper limit of normal range participated in a double-blind, placebo-controlled study. While continuing on UDCA, the patients were randomised to two 3-month crossover treatment periods with placebo and OCA, in random order, separated by a 1-month washout period without study treatment. After each of the two treatment periods, we determined rate constants for transport of conjugated bile acids between blood, hepatocytes, biliary canaliculi, and bile ducts by positron emission tomography of the liver using the conjugated bile acid tracer [N-methyl-11C]cholylsarcosine (11C-CSar). The hepatic blood perfusion was measured using infusion of indocyanine green and Fick's principle. RESULTS: Compared with placebo, OCA increased hepatic blood perfusion by a median of 11% (p = 0.045), the unidirectional uptake clearance of 11C-CSar from blood into hepatocytes by a median of 11% (p = 0.01), and the rate constant for secretion of 11C-CSar from hepatocytes into biliary canaliculi by a median of 73% (p = 0.03). This resulted in an OCA-induced decrease in the hepatocyte residence time of 11C-CSar by a median of 30% (p = 0.01), from group median 11 min to 8 min. CONCLUSIONS: This study of UDCA-treated patients with PBC showed that, compared with placebo, OCA increased the hepatic transport of the conjugated bile acid tracer 11C-CSar, and thus endogenous conjugated bile acids, from hepatocytes into biliary canaliculi. As a result, OCA reduced the time hepatocytes are exposed to potentially cytotoxic bile acids. LAY SUMMARY: Primary biliary cholangitis is a chronic liver disease in which the small bile ducts are progressively destroyed. We tested whether the treatment with obeticholic acid (OCA) would improve liver excretion of bile acids compared with placebo in 8 patients with primary biliary cholangitis. A special scanning technique (PET scan) showed that OCA increased the transport of bile acids from blood to bile. OCA thereby reduced the time that potentially toxic bile acids reside in the liver by approximately one-third.

Regulation of Intestinal UDP-Glucuronosyltransferase 1A1 by the Farnesoid X Receptor Agonist Obeticholic Acid Is Controlled by Constitutive Androstane Receptor through Intestinal Maturation.

UDP-glucuronosyltransferase (UGT) 1A1 is the only transferase capable of conjugating serum bilirubin. However, temporal delay in the development of the UGT1A1 gene leads to an accumulation of serum bilirubin in newborn children. Neonatal humanized UGT1 (hUGT1) mice, which accumulate severe levels of total serum bilirubin (TSB), were treated by oral gavage with obeticholic acid (OCA), a potent FXR agonist. OCA treatment led to dramatic reduction in TSB levels. Analysis of UGT1A1 expression confirmed that OCA induced intestinal and not hepatic UGT1A1. Interestingly, Cyp2b10, a target gene of the nuclear receptor CAR, was also induced by OCA in intestinal tissue. In neonatal hUGT1/Car -/- mice, OCA was unable to induce CYP2B10 and UGT1A1, confirming that CAR and not FXR is involved in the induction of intestinal UGT1A1. However, OCA did induce FXR target genes, such as Shp, in both intestines and liver with induction of Fgf15 in intestinal tissue. Circulating FGF15 activates hepatic FXR and, together with hepatic Shp, blocks Cyp7a1 and Cyp7b1 gene expression, key enzymes in bile acid metabolism. Importantly, the administration of OCA in neonatal hUGT1 mice accelerates intestinal epithelial cell maturation, which directly impacts on induction of the UGT1A1 gene and the reduction in TSB levels. Accelerated intestinal maturation is directly controlled by CAR, since induction of enterocyte marker genes sucrase-isomaltase, alkaline phosphatase 3, and keratin 20 by OCA does not occur in hUGT1/Car -/- mice. Thus, new findings link an important role for CAR in intestinal UGT1A1 induction and its role in the intestinal maturation pathway. SIGNIFICANCE STATEMENT: Obeticholic acid (OCA) activates FXR target genes in both liver and intestinal tissues while inducing intestinal UGT1A1, which leads to the elimination of serum bilirubin in humanized UGT1 mice. However, the induction of intestinal UGT1A1 and the elimination of bilirubin by OCA is driven entirely by activation of intestinal CAR and not FXR. The elimination of serum bilirubin is based on a CAR-dependent mechanism that facilitates the acceleration of intestinal epithelium cell differentiation, an event that underlies the induction of intestinal UGT1A1.

Discovery and Optimization of Non-bile Acid FXR Agonists as Preclinical Candidates for the Treatment of Nonalcoholic Steatohepatitis.

Farnesoid X receptor (FXR) plays a key role in bile acid homeostasis, inflammation, fibrosis, and metabolism of lipid and glucose and becomes a promising therapeutic target for nonalcoholic steatohepatitis (NASH) or other FXR-dependent diseases. The phase III trial results of obeticholic acid demonstrate that the FXR agonists emerge as a promising intervention in patients with NASH and fibrosis, but this bile acid-derived FXR agonist brings severe pruritus and an elevated risk of cardiovascular disease for patients. Herein, we reported our efforts in the discovery of a series of non-bile acid FXR agonists, and 36 compounds were designed and synthesized based on the structure-based drug design and structural optimization strategies. Particularly, compound 42 is a highly potent and selective FXR agonist, along with good pharmacokinetic profiles, high liver distribution, and preferable in vivo efficacy, indicating that it is a potential candidate for the treatment of NASH or other FXR-dependent diseases.

Controlled Delivery of Bile Acids to the Colon.

INTRODUCTION: Bile acids, such as chenodeoxycholic acid, play an important role in digestion but are also involved in intestinal motility, fluid homeostasis, and humoral activity. Colonic delivery of sodium chenodeoxycholate (CDC) has demonstrated clinical efficacy in treating irritable bowel syndrome with constipation but was associated with a high frequency of abdominal pain. We hypothesized that these adverse effects were triggered by local super-physiological CDC levels caused by an unfavorable pharmacokinetic profile of the delayed release formulation. METHODS: We developed novel release matrix systems based on hydroxypropyl methylcellulose (HPMC) for sustained release of CDC. These included standard HPMC formulations as well as bi-layered formulations to account for potential delivery failures due to low colonic fluid in constipated patients. We evaluated CDC release profiles in silico (pharmacokinetic modeling), in vitro and in vivo in swine (pharmacokinetics, rectal manometry). RESULTS: For the delayed release formulation in vitro release studies demonstrated pH triggered dose dumping which was associated with giant colonic contractions in vivo. Release from the bi-layered HPMC systems provided controlled release of CDC while minimizing the frequency of giant contractions and providing enhanced exposure as compared to standard HPMC formulations in vivo. DISCUSSION: Bi-phasic CDC release could help treat constipation while mitigating abdominal pain observed in previous clinical trials. Further studies are necessary to demonstrate the therapeutic potential of these systems in humans.

Metabolism of obeticholic acid in brown bullhead (Ameiurus nebulosus).

Analysis of brown bullhead (Ameiurus nebulosus) bile by ultra performance liquid chromatography high-resolution mass spectrometry (UPLC/HRMS) revealed a series of bile acids similar to those found in humans. Accordingly, we chose this fish as a model organism to examine the metabolism of obeticholic acid, a bile acid used to treat a number of human liver diseases and the one that has the potential to occur as an environmental contaminant. The taurine and glycine conjugates of obeticholic acid and keto-obeticholic acid were identified, as well as the D-cysteinolic acid conjugate of obeticholic acid, likely a metabolite specific to fish. In addition, metabolites of obeticholic acid (sulphate and glucuronide) and several hydroxy-obeticholic acid derivatives were found, representing typical pathways of primary and secondary steroid metabolism. Brown bullhead exposed to obeticholic acid at a dose of 100 mg/kg gave no overt signs of distress or toxicity.

An ultra-performance liquid chromatography-tandem mass spectrometry method for the determination of obeticholic acid in rat plasma and its application in preclinical pharmacokinetic studies.

Currently, ursodeoxycholic acid (UDCA) is the only clear medical treatment for primary biliary cholangitis (PBC). However, approximately 40% of patients are not sensitive to UDCA. In recent years, obeticholic acid (OCA) combined with UDCA has been used in the PBC patients who were not sensitive to UDCA, or as monotherapy for PBC adult patients who are intolerant to UDCA. OBJECTIVE: To develop and validate a specific, sensitive and reliable tandem mass spectrometry (UPLC-MS/MS) method for the determination of obeticholic acid (OCA) in rat plasma. METHODS: Plasma samples were treated with liquid-liquid extraction. Diazepam was selected as the internal standard (IS). Chromatographic separation was achieved by an Acquity BEH C18 column (2.1 mm × 50 mm, 1.7 µm) and a mobile phase consisting of acetonitrile and ultrapure water (containing 0.1% formic acid). The analyte was detected in positive ion mode by electrospray ionization mass spectrometry (ESI-MS). Multiple reaction monitoring (MRM) methods were used to detect specific precursor and product ions. The target ion pair of OCA was 419.38 → 401.22, and the IS was 285.05 → 193.02. RESULTS: The linear range of OCA in rat plasma was 0.05-50 µg/mL (R2 = 0.992); the recovery rate was 91.34%-97.37%. This assay showed good intra- and inter-day precision and accuracy. No significant matrix effects in this study. CONCLUSION: A specific, sensitive and reliable quantitative analysis method was established to detect OCA after oral/intravenous administration in rat plasma via UPLC-MS/MS. It was appropriate for preclinical pharmacokinetic studies of OCA.

FXR-Dependent Modulation of the Human Small Intestinal Microbiome by the Bile Acid Derivative Obeticholic Acid.

BACKGROUND & AIMS: Intestinal bacteria can modify the composition of bile acids and bile acids, which are regulated by the farnesoid X receptor, affect the survival and growth of gut bacteria. We studied the effects of obeticholic acid (OCA), a bile acid analogue and farnesoid X receptor agonist, on the intestinal microbiomes of humans and mice. METHODS: We performed a phase I study in 24 healthy volunteers given OCA (5, 10, or 25 mg/d for 17 days). Fecal and plasma specimens were collected at baseline (day 0) and on days 17 (end of dosing) and 37 (end of study). The fecal specimens were analyzed by shotgun meta-genomic sequencing. A Uniref90 high-stringency genomic analysis was used to assign specific genes to the taxonomic signature of bacteria whose abundance was associated with OCA. Male C57BL/6 mice were gavage fed daily with water, vehicle, or OCA (10 mg/kg) for 2 weeks. Small intestine luminal contents were collected by flushing with saline and fecal pellets were collected at baseline and day 14. Mouse samples were analyzed by 16S-tagged sequencing. Culture experiments were performed to determine the taxonomic-specific effects of bile acids and OCA on bacterial growth. RESULTS: Suppression of endogenous bile acid synthesis by OCA in subjects led to a reversible induction of gram-positive bacteria that are found in the small intestine and are components of the diet and oral microbiota. We found that bile acids decreased proliferation of these bacteria in minimum inhibitory concentration assays. In these organisms, there was an increase in the representation of microbial genomic pathways involved in DNA synthesis and amino acid metabolism with OCA treatment of subjects. Consistent with these findings, mice fed OCA had lower endogenous bile acid levels and an increased proportion of Firmicutes, specifically in the small intestine, compared with mice fed water or vehicle. CONCLUSIONS: In studying the effects of OCA in humans and mice, we found evidence for interactions between bile acids and features of the small intestinal microbiome. These findings indicate that farnesoid X receptor activation alters the intestinal microbiota and could provide opportunities for microbiome biomarker discovery or new approaches to engineering the human microbiome. ClinicalTrials.gov, NCT01933503.

Assessment of Pharmacokinetic Interactions Between Obeticholic Acid and Caffeine, Midazolam, Warfarin, Dextromethorphan, Omeprazole, Rosuvastatin, and Digoxin in Phase 1 Studies in Healthy Subjects.

INTRODUCTION: Obeticholic acid (OCA), a potent and selective farnesoid X receptor agonist, is indicated for the treatment of primary biliary cholangitis (PBC). We investigated the potential drug-drug interaction effect of OCA on metabolic CYP450 enzymes and drug transporters. METHODS: Five phase 1 single-center, open-label, fixed-sequence, inpatient studies were conducted in healthy adult subjects to evaluate the effect of oral daily doses of 10 or 25 mg OCA on single-dose plasma pharmacokinetics of specific probe substrates for enzymes CYP1A2 (caffeine, R-warfarin), CYP3A (midazolam, R-warfarin), CYP2C9 (S-warfarin), CYP2D6 (dextromethorphan), CYP2C19 (omeprazole), and drug transporters, BCRP/OATP1B1/OATP1B3 (rosuvastatin), and P-gp (digoxin). RESULTS: OCA showed no substantial suppression/inhibition of S-warfarin, digoxin, and dextromethorphan and weak interactions with caffeine, omeprazole, rosuvastatin, and midazolam. The maximal pharmacodynamic responses (E max) to warfarin-based INR, PT, and aPTT were reduced by 11%, 11%, and 1%, respectively, for the 10-mg dose group and by 7%, 7% and 0%, respectively, for the 25-mg dose group. Overall, drugs dosed in combination with OCA were well tolerated, and most adverse events were mild in severity. No clinically important trends were noted in laboratory evaluations, vital signs, or 12-lead ECGs. CONCLUSION: In these studies, OCA showed weak to no suppression/inhibition of metabolic enzymes and drug transporters at the highest recommended therapeutic dose in patients with PBC. On the basis on these analyses, monitoring and maintenance of target INR range are required during coadministration of OCA with drugs that are metabolized by CYP1A2 (R-warfarin). FUNDING: Intercept Pharmaceuticals, Inc.

Modeling and Experimental Studies of Obeticholic Acid Exposure and the Impact of Cirrhosis Stage.

Obeticholic acid (OCA), a semisynthetic bile acid, is a selective and potent farnesoid X receptor (FXR) agonist in development for the treatment of chronic nonviral liver diseases. Physiologic pharmacokinetic models have been previously used to describe the absorption, distribution, metabolism, and excretion (ADME) of bile acids. OCA plasma levels were measured in healthy volunteers and cirrhotic subjects. A physiologic pharmacokinetic model was developed to quantitatively describe the ADME of OCA in patients with and without hepatic impairment. There was good agreement between predicted and observed increases in systemic OCA exposure in subjects with mild, moderate, and severe hepatic impairment, which were 1.4-, 8-, and 13-fold relative to healthy volunteers. Predicted liver exposure for subjects with mild, moderate, and severe hepatic impairment were increased only 1.1-, 1.5-, and 1.7-fold. In subjects with cirrhosis, OCA exposure in the liver, the primary site of pharmacological activity along with the intestine, is increased marginally (∼2-fold).

The role of the bile acid chenodeoxycholic acid in the targeted oral delivery of the anti-diabetic drug gliclazide, and its applications in type 1 diabetes.

Gliclazide (G) is used to treat type 2 diabetes (T2D), and also has anti-platelet, anti-radical, and anti-inflammatory effects. G has poor water solubility and high inter-individual variations in absorption, limiting its application in type 1 diabetes (T1D). The bile acid, chenodeoxycholic acid (CDCA), has permeation-enhancing effects. Sodium alginate (SA) was used to microencapsulate G and CDCA to produce control (G-SA) and test (G-CDCA-SA) microcapsules. Both microcapsules showed uniform structure, morphology, and good stability profiles. CDCA reduced G-release at pH 7.8, while G-release was negligible at lower pH values in both microcapsules. CDCA incorporation resulted in less swelling and stronger microcapsules, suggesting improved stability.

Absorption Mechanism of a Physical Complex of Monomeric Insulin and Deoxycholyl-l-lysyl-methylester in the Small Intestine.

Currently, oral administration of insulin still remains the best option to avoid the burden of repeated subcutaneous injections and to improve its pharmacokinetics. The objective of the present investigation was to demonstrate the absorption mechanism of insulin in the physical complexation of deoxycholyl-l-lysyl-methylester (DCK) for oral delivery. The oral insulin/DCK complex was prepared by making a physical complex of insulin aspart with DCK through ion-pair interaction in water. For the cellular uptake study, fluorescein-labeled insulin or DCK were prepared according to a standard protocol and applied to Caco-2 or MDCK cell lines. For the PK/PD studies, we performed intrajejunal administration of different formulation of insulin/DCK complex to diabetic rats. The resulting insulin and DCK complex demonstrated greatly enhanced lipophilicity as well as increased permeation across Caco-2 monolayers. The immunofluorescence study revealed the distribution of the complex in the cytoplasm of Caco-2 cells. Moreover, in the apical sodium bile acid transporter (ASBT) transfected MDCK, the insulin/DCK complex showed interaction with ASBT, and also demonstrated absorption through passive diffusion. We could not find that any evidence of endocytosis in relation to the uptake of insulin complex in vitro. In the rat intestine model, the highest absorption of insulin complex was observed in the jejunum at 1 h and then in the ileum at 2-4 h. In PK/PD study, the complex showed a similar PK profile to that of SC insulin. Overall, the study showed that the effect of DCK on enhancing the absorption of insulin resulted from transcellular processes as well as bile acid transporter activity.

Kinetics of primary bile acids in patients after proctocolectomy and ileal pouch-anal anastomosis.

BACKGROUND: The high incidence of cholesterol gallstones in patients after proctocolectomy with ileal pouch-anal anastomosis (IPAA) may be due to an increased loss of bile acids. We aimed to evaluate the kinetics of the primary bile acids cholic acid (CA) and chenodeoxycholic acid (CDCA) in these patients. METHODS: Pool sizes, synthesis rates, and fractional turnover rates of CA and CDCA were determined by combined capillary gas chromatography/isotope ratio mass spectrometry in serum samples after administration of [¹³C]CA and [¹³C]CDCA in 6 patients and 9 healthy volunteers. RESULTS: In patients with IPAA, pool sizes of CA and CDCA were 11.5 (8.2-23.8) and 12.1 (6.7-20.1) µmol/kg, respectively, and were significantly lower than in healthy controls [36.0 (24-47) and 29.0 (21-42) µmol/kg, respectively; p < 0.05, each]. Fractional turnover rates of CA [1.19 (1.06-1.82) vs. 0.31 (0.13-0.54) per day] and CDCA [1.01 (0.50-1.63) vs. 0.23 (0.09-0.36) per day] were increased fourfold in patients with IPAA (p < 0.05, each). Synthesis rates of CDCA [10.2 (5.2-32.9) vs. 6.6 (2.7-10.5) µmol/kg per day, p = 0.05] and CA [15.1 (9.3-39.4) vs. 11.5 (3.1-20.5) µmol/kg per day, n.s.] tended to be higher in patients with IPAA than in controls. CONCLUSION: The reduced pool size of primary bile acids may contribute to the high incidence of cholesterol gallstones in patients after proctocolectomy and IPAA.

Pharmacodynamic and clinical endpoints for functional colonic disorders: statistical considerations.

BACKGROUND: Intra- and inter-subject coefficients of variation (COV) of scintigraphic colonic transit (SCT) are well characterized. SCT response to therapy predicts clinical efficacy of experimental medications in lower functional gastrointestinal disorders (FGID). AIM: To compare COVs for bowel function with pharmacodynamic (PD) colonic transit geometric center (GC) as endpoints in lower FGID studies. METHODS: We evaluated data from placebo arm of 9 phase IIA, parallel-group, clinical trials of PD effects of linaclotide, dexloxiglumide, renzapride, elobixibat, ROSE 010, and chenodeoxycholate in lower FGID with constipation, and pexacerafont, VSL#3, and colesevelam in lower FGID with diarrhea. Patients completed daily diaries for at least 7 days of stool frequency, consistency (7-point Bristol Stool Form Scale), and ease of passage (7-point scale from manual disimpaction to incontinence). Seventeen patients received placebo in 2 separate studies allowing assessment of intra-patient COVs. We calculated sample sizes required to demonstrate a 30 % effect size for colonic transit, stool frequency, consistency and ease of passage for patients with lower FGID with constipation and, separately, diarrhea. RESULTS: COV(inter) from 87 patients and COV(intra) from 17 patients are reported. Generally, COV(intra) is somewhat greater than COV(inter). The COVs for PD endpoints are lower than for clinical endpoints; however, clinically relevant effects can be identified with modest (~50 %) increases in the sample size using parallel-group design studies. CONCLUSION: Phase IIA studies that incorporate clinical and PD endpoints are feasible in lower FGID associated with constipation or diarrhea. Crossover design would require lower sample size for most endpoints compared to parallel-group studies.

Farnesoid X receptor agonist for the treatment of liver and metabolic disorders: focus on 6-ethyl-CDCA.

6-ethyl-chedeoxycholic acid (6E-CDCA) is a farnesoid X receptor (FXR) ligand endowed with agonistic activity under development for treatment of cholestatic liver diseases including primary biliary cirrhosis (PBC) and liver-related metabolic disorders including non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). FXR is a bile sensor that acts in coordination with other nuclear receptors to regulate essential steps of bile acid uptake, metabolism and excretion. 6E-CDCA has been investigated in preclinical models of cholestasis, liver fibrosis and diet-induced atherosclerosis. In a phase II clinical trial in patients with PBC, 6E-CDCA met the primary endpoint of a reduction in alkaline phosphatase levels but safety data indicated that the drug exacerbated pruritus, one of the main symptoms of PBC, suggesting that 6E-CDCA or FXR are mediators of pruritus in humans. Treatment of patients with diabetes and liver steatosis resulted in amelioration of insulin sensitivity despite a reduction a slight reduction in HDL and increased levels of LDL were observed. These side effects on bile acids and lipid metabolism were all predicted by pre-clinical studies, suggesting that potent FXR ligands hold promise but potential side effects might limit their development.

Structural determinants for transport across the intestinal bile acid transporter using C-24 bile acid conjugates.

The human apical sodium dependent bile acid transporter (hASBT) reabsorbs gram quantities of bile acid daily and is a potential prodrug target to increase oral drug absorption. In the absence of a high resolution hASBT crystal structure, 3D-QSAR modeling may prove beneficial in designing prodrug targets to hASBT. The objective was to derive a conformationally sampled pharmacophore 3D-QSAR (CSP-SAR) model for the uptake of bile acid conjugates by hASBT. A series of bile acid conjugates of glutamyl chenodeoxycholate were evaluated in terms of K(m) and normalized V(max) (normV(max)) using hASBT-MDCK cells. All monoanionic conjugates were potent substrates. Dianions, cations and zwitterions, which bound with a high affinity, were not substrates. CSP-SAR models were derived using structural and physicochemical descriptors, and evaluated via cross validation. The best CSP-SAR model for K(m) included two structural and two physiochemical descriptors, where substrate hydrophobicity enhanced affinity. A best CSP-SAR model for K(m)/normV(max) employed one structural and three physicochemical descriptors, also indicating hydrophobicity enhanced efficiency. Overall, the bile acid C-24 region accommodated a range of substituted anilines, provided a single negative charge was present near C-24. In comparing uptake findings to prior inhibition results, increased hydrophobicity enhanced activity, with dianions and zwitterions hindering activity.

Chenodeoxycholate in females with irritable bowel syndrome-constipation: a pharmacodynamic and pharmacogenetic analysis.

BACKGROUND & AIMS: Sodium chenodeoxycholate (CDC) accelerates colonic transit in health. Our aim was to examine pharmacodynamics (colonic transit, bowel function) and pharmacogenetics of CDC in constipation-predominant irritable bowel syndrome (IBS-C). METHODS: In a double-blind placebo-controlled study, 36 female patients with IBS-C were randomized to treatment with delayed-release oral formulations of placebo, 500 mg CDC, or 1000 mg CDC for 4 days. We assessed gastrointestinal and colonic transit, stool characteristics, and associations of transit with fasting serum 7αC4 (surrogate of bile acid synthesis) and FGF19 (negative regulator of bile acid synthesis) levels. Candidate genetic polymorphisms involved in regulation of bile acid synthesis were analyzed in the 36 patients with IBS-C and 57 healthy volunteers to assess genetic influence on effects of CDC on transit. RESULTS: Overall colonic transit and ascending colon emptying (AC t(½)) were significantly accelerated in the CDC group compared with placebo (P = .005 and P = .028, respectively). Looser stool consistency (P = .003), increased stool frequency (P = .018), and greater ease of passage (P = .024) were noted with CDC compared with placebo. The most common side effect was lower abdominal cramping/pain (P = .01). Fasting serum 7αC4 (but not FGF19) was positively associated with colonic transit (r(s) = 0.749, P = .003, placebo group). Genetic variation in FGFR4 was associated with AC t(½) in response to CDC (uncorrected P = .015); αKlothoß variant showed a gene-by-treatment interaction based on patient subgroup (uncorrected P = .0088). CONCLUSIONS: CDC accelerates colonic transit and improves bowel function in female patients with IBS-C. The rate of bile acid synthesis influences colonic transit. Genetic variation in negative feedback inhibition of bile acid synthesis may affect CDC-mediated acceleration of colonic transit.

Cefotaxime pharmacokinetics after oral application in the form of 3alpha,7alpha-dihydroxy-12-keto-5beta-cholanate microvesicles in rat.

The aim of ths study was to investigate the pharmacokinetics of cefotaxime sodium (CEF) pharmacokinetics after oral application in the form of sodium 3alpha,7alpha-dihydroxy-12-keto-5beta-cholanate (MKC) microvesicles (MV) in rat. Thirty Male Wister rats were divided into six groups (n=5 per group). Groups were treated orally with: (i) CEF (15 mg/kg) saline solution (15 mg/kg); (ii) CEF (15 mg/kg) saline solution with MKC (2 mg/kg); (iii) CEF saline solution mixed with blank microvesicles; (iv) CEF (15 mg/kg) encapsulated in microvesicles with saline solution; (v) CEF saline solution (15 mg/kg) mixed with blank MKC microvesicules; (vi) CEF (15 mg/kg) encapsulated in MKC microvesicules with saline solution. Data were analyzed using noncompartmental model. CEF oral bioavailability was increased twofold when coadministered with MKC and when encapsulated in microvesicles and ninefold when encapsulated in MKC microvesicles compared to the same CEF dose administered orally as saline solution. The increased bioavailability of CEF resulting from CEF encapsulation in microvesicules with MKC suggests that this formulation can extend the application of CEF from parenteral only to oral application.