BASTA trial: protocol for a randomised, double-blind, placebo-controlled, crossover trial investigating the effects of atorvastatin on bile acid diarrhoea.

Abstract

Bile acid diarrhoea (BAD) is a chronic disease with typical symptoms of daily watery stools with increased frequency and urgency. BAD arises due to pathologically high levels of bile acids in the colon, which may be due to impaired reabsorption or increased synthesis. Evidence indicates that atorvastatin administration suppresses bile acid synthesis in healthy individuals, likely due to reduced substrate availability. The Bile Acid diarrhoea STAtin Trial aims to investigate whether atorvastatin treatment reduces bile acid synthesis in patients with BAD and consequently alleviates BAD symptoms. 20 adults with moderate-to-severe BAD, assessed by the gold standard diagnostic test ⁷⁵selenium homotaurocholic acid test, will be randomised to begin with either placebo or atorvastatin 40 mg once daily for 2 weeks, followed by 80 mg once daily for another 2 weeks. After a 4-week washout period, participants will cross over to the alternate treatment. The primary endpoint is the relative difference between atorvastatin and placebo treatment in bile acid synthesis rate, measured by the validated biomarker 7alpha-hydroxy-4-cholesten-3-one (C4) and key secondary endpoints include mean differences in daily stool frequency. The study is approved by the Danish Medicines Agency and the Regional Scientific Ethics Committee of the Capital Region of Denmark (2025-521 856-47-00) and registered with the Danish Data Protection Agency (p-2024-17870). The study is monitored by the Capital Region of Denmark's Good Clinical Practice unit. All results will be disseminated at national and/or international scientific meetings and in peer-reviewed scientific journals. NCT07042165.