Conditions: Primary Bile Acid Malabsorption Secondary Bile Acid Malabsorption Chronic Diarrhoea
Keywords: Primary bile acid malabsorption Secondary bile acid malabsorption Chronic diarrhoea Obeticholic acid SeHCAT FXR FGF19
Allocation: NON_RANDOMIZED | Intervention model: SINGLE_GROUP
Enrollment: 35
Healthy volunteers: no

Brief summary:
The investigators propose to develop studies of obeticholic acid (OCA) in patients with bile acid diarrhoea. OCA is a semisynthetic bile acid, also known as 6αethylchenodeoxycholic acid or INT747,and is a potent farnesoid X receptor (FXR) agonist. Preliminary data suggests that patients with bile acid diarrhoea have impaired production of the ileal hormone Fibroblast Growth Factor 19 (FGF19). FGF19 is stimulated by FXR agonists, and regulates bile acid synthesis. This study is a pilot, proof-of-concept, open-label study to investigate whether OCA can stimulate FGF19 in bile acid diarrhoea patients to provide a safe and effective treatment.

Detailed description:
Bile acid diarrhoea (BAD) is an under-recognised but common condition of chronic watery diarrhoea. BAD may be secondary to ileal disease affecting the reabsorption and the enterohepatic circulation of bile acids (bile acid malabsorption) or can be an idiopathic, primary BAD (PBAD). In work published in 2009, we described a new mechanism to explain this syndrome of primary BAD.

Blood levels of the hormone fibroblast growth factor 19 (FGF19) are reduced in primary and secondary BAD, producing impaired feedback inhibition of bile acid synthesis, leading to excess faecal bile acids, which then produce diarrhoea by stimulating colonic secretion. FGF19 is synthesised in the ileum and we have shown transcription is markedly induced by farnesoid X receptor(FXR) agonists such as chenodeoxycholic acid, an abundant natural bile acid. More potent FXR agonists are logical diagnostic and therapeutic agents for this condition, and obeticholic acid (OCA), which is 100x more potent than chenodeoxycholic acid, has recently been developed. It has been used in phase II studies in primary biliary cirrhosis and in non-alcoholic steatohepatitis where a relatively common side-effect was constipation.

We aim to investigate the effects of OCA in patients with primary and secondary BAD to determine whether FGF19 is able to be stimulated in these conditions. We will compare these responses to those in control patients with chronic diarrhoea but without evidence of BAD. It is possible in BAD that the defect in FGF19 levels is due to an inability to respond to FXR stimulation (particularly likely in secondary BAD after ileal resection). Patients with primary BAD may be able to respond and benefit from an increase in FGF19 levels.

This study aims to obtain pilot data on the effects of OCA on FGF19, other markers of bile acid metabolism and patient symptoms including diarrhoea. These are early phase II, proof of concept studies.

Arms:
arm 1: Defined as SeHCAT \<10% without other causes such as Crohn's disease and/or ileal resection arm 2: With Crohn's disease or ileal resection arm 3: Chronic diarrhoea with SeHCAT \>15% and no Crohn's or ileal resection

Interventions: intervention 1: Obeticholic acid
Intervention descriptions: intervention 1: Day -14 to Day 0 subjects will stop their usual diarrhoeal medication. Day 1 to Day 15 Obeticholic acid 25mg tablet will be administered to subjects once daily in the morning. Day 16 to day 28 normal diarrhoeal medication may be re-commenced.

Protocol document: