Differences in the efficacy of ursodeoxycholic acid and bile acid metabolism between viral liver diseases and primary biliary cirrhosis

Bile acids and signal transduction: role in glucose homeostasis

Bile acids are mainly recognized for their role in dietary lipid absorption and cholesterol homeostasis. However, recent progress in bile acid research suggests that bile acids are important signaling molecules that play a role in glucose homeostasis. Among the various supporting evidence, several reports have demonstrated an improvement of the glycemic index of type 2 diabetic patients treated with diverse bile acid binding resins. Herein, we review the diverse interactions of bile acids with various signaling/response pathways, including calcium mobilization and protein kinase activation, membrane receptor-mediated responses, and nuclear receptor responses. Some of the effects of the bile acids are direct through the activation of specific receptors, i.e., TGR5, CAR, VDR, and FXR, while others imply modulation of the hormonal, growth factor and/or neuromediator responses, i.e., glucagon, EGF, and acetylcholine. We also discuss recent evidence implicating the interaction of bile acids with glucose homeostasis mechanisms, with the integration of our understanding of how the signaling mechanisms modulated by bile acid could regulate glucose metabolism.

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.

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Cholestatic syndromes

Further insights into the molecular regulation of bile acid transport and metabolism have provided the basis for a better understanding of the pathogenesis of cholestatic liver diseases. Novel insights into the mechanisms of action of ursodeoxycholic acid should advance our understanding of the treatment of cholestatic liver diseases. Mutations of transporter genes can cause hereditary cholestatic syndromes in both infants and adults as well as cholesterol gallstone disease. Important studies have been published on the pathogenesis, clinical features, and treatment of primary biliary cirrhosis, drug-induced cholestasis, and cholestasis of pregnancy.