Abstract
AIMS: Elobixibat is a minimally absorbed ileal bile acid transporter inhibitor. This study aimed to investigate the safety, tolerability, efficacy, pharmacokinetics and pharmacodynamics of elobixibat in Japanese patients with chronic constipation. METHODS: This study consisted of single-dose and multiple-dose tests with a dose-escalating design. Sixty patients including females and males were randomized into five dose levels of elobixibat (2.5, 5, 10, 15 or 20 mg, n = 10 per level) and corresponding placebo (n = 2 per group). A crossover design was used to examine food effect in single-dose test. Patients received test tablets once daily for 14 days in multiple-dose test. We assessed pharmacokinetic-dose proportionality, levels of serum high- and low-density lipoprotein cholesterol and plasma 7α-hydroxy-4-cholesten-3-one (C4), food effect and sex-specific effect. Adverse events and bowel functions such as bowel movements, stool consistency and straining were also evaluated. RESULTS: Food consumption reduced systemic exposure by around 80% [e.g. least squares mean (ratio of breakfast/no breakfast) maximum plasma concentration: 0.2085 (90% confidence interval, 0.1371-0.3172) at 15 mg] while increased plasma C4 level (P < 0.001). In the multiple-dose test, elobixibat reduced low-density lipoprotein cholesterol and increased C4 whilst unaltering high-density lipoprotein cholesterol level. The increased spontaneous bowel movement frequency was correlated with higher dosage and higher C4 level (R(2) = 0.5929 at Week 2). Adverse events were mainly gastrointestinal symptoms, most of which were mild. CONCLUSIONS: Elobixibat should be taken before breakfast. Once-daily administration of elobixibat was found to be safe and tolerated up to 20 mg in female and male patients with chronic constipation.