Effect of colestimide on intestinal absorption of ursodeoxycholic acid in men

Active enterohepatic cycling is not required for the choleretic actions of 24-norUrsodeoxycholic acid in mice

The pronounced choleretic properties of 24-norUrsodeoxycholic acid (norUDCA) to induce bicarbonate-rich bile secretion have been attributed to its ability to undergo cholehepatic shunting. The goal of this study was to identify the mechanisms underlying the choleretic actions of norUDCA and the role of the bile acid transporters. Here, we show that the apical sodium-dependent bile acid transporter (ASBT), organic solute transporter-α (OSTα), and organic anion transporting polypeptide 1a/1b (OATP1a/1b) transporters are dispensable for the norUDCA stimulation of bile flow and biliary bicarbonate secretion. Chloride channels in biliary epithelial cells provide the driving force for biliary secretion. In mouse large cholangiocytes, norUDCA potently stimulated chloride currents that were blocked by siRNA silencing and pharmacological inhibition of calcium-activated chloride channel transmembrane member 16A (TMEM16A) but unaffected by ASBT inhibition. In agreement, blocking intestinal bile acid reabsorption by coadministration of an ASBT inhibitor or bile acid sequestrant did not impact norUDCA stimulation of bile flow in WT mice. The results indicate that these major bile acid transporters are not directly involved in the absorption, cholehepatic shunting, or choleretic actions of norUDCA. Additionally, the findings support further investigation of the therapeutic synergy between norUDCA and ASBT inhibitors or bile acid sequestrants for cholestatic liver disease.

[In-vitro study of the drug interactions between Miglitol, an alpha-glucosidase inhibitor, and adsorbents]

The interactions between miglitol, an alpha-glucosidase inhibitor, and six adsorbents (carbon spheres, cholestyramine, colestimide, sevelamer hydrochloride, calcium polystyrene sulfonate, and sodium polystyrene sulfonate) were investigated in vitro. Miglitol corresponding to the minimum dose and adsorbents corresponding to the maximum dose were incubated at 37 degrees C for 180 min in solutions of pH 1.2 (gastric pH condition) and pH 6.8 (enteric pH condition), with and without the presence of carbohydrates, which were added to observe the effects on food adsorption. The adsorption ratio of miglitol to carbon spheres was 13.6% and 0% in pH 1.2 solution and 86.4% and 5.0% in pH 6.8 solution without and with the presence of carbohydrates, respectively. Thus, the adsorption ratio was higher in pH 6.8 solution. Adsorption of miglitol to calcium polystyrene sulfonate was nearly the same, 15.0-21.9%, at both pH. The adsorption ratio of miglitol to sodium polystyrene sulfonate was 43.4% and 45.5%, respectively, in pH 1.2 solution without and with carbohydrates. In the pH 6.8 solutions, however, the respective adsorption ratios were low (5.2% and 11.3%). Miglitol did not adsorb to cholestyramine, sevelamer hydrochloride or colestimide under any pH condition examined. The above results suggest that miglitol adsorbs to carbon spheres and polystyrene sulfonic acid cation exchange resins. However, considering that miglitol is taken just before eating and thus exists in gastointestinal fluids together with food, and that the site of its effect is the upper small intestine, the interactions between miglitol and these adsorbents will most likely not be a problem.

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

BACKGROUND

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Inhibition of ileal bile acid absorption by colestimide

BACKGROUND

Colestimide is a new type of anion-exchange resin in Japan, but its effect on bile acid absorption in the ileum has not been studied.

METHODS

Absorption of ursodeoxycholate, tauroursodeoxycholate, cholate, taurocholate and taurolithocholate-sulfate in rat ileum was compared in the presence and absence of colestimide. Bile acid adsorption by colestimide in vitro was also studied.

RESULTS

All bile acids were efficiently absorbed by the ileum, and the cumulative absorption during 60 min was 25-78%. The absorption of ursodeoxycholate, tauroursodeoxycholate and taurocholate was inhibited by colestimide, whereas that of cholate and taurolithocholate-sulfate was not inhibited by colestimide. Adsorption of bile acids by colestimide in vitro was higher with taurine conjugates than with the unconjugated forms.

CONCLUSIONS

Colestimide was shown to be useful to inhibit the physiologically important ileal absorption of bile acid amides in vivo.

Effect of colestimide on absorption of unconjugated bile acids in the rat jejunum

BACKGROUND

Colestimide is a newly developed bile acid-binding resin in Japan, but its bile acid-binding properties have not been studied.

METHODS

The absorption of unconjugated bile acids (5 mmol/L) in the ligated rat jejunum was compared in the presence and absence of colestimide. Furthermore, bile acid adsorption by colestimide was also studied in vitro.

RESULTS

All bile acids were efficiently absorbed in the jejunum and the cumulative absorption during 120 min was 29-63%. The absorption of chenodeoxycholate, lithocholate, deoxycholate and ursodeoxycholate was dose-dependently inhibited by 2.5 and 5 mg colestimide, whereas the absorption of cholate was not inhibited, even in the presence of 5 mg colestimide. Adsorption of bile acids by colestimide in vitro was approximately 60% for chenodeoxycholate, lithocholate, deoxycholate and ursodeoxycholate, whereas the adsorption of cholate was low (16%).

CONCLUSIONS

Jejunal absorption of ursodeoxycholate was inhibited by colestimide to a similar extent as other dihydroxy bile acids, whereas that of cholate was not inhibited under the same conditions.