Liver Injury with Ulipristal Acetate: Exploring the Underlying Pharmacological Basis

The European Medicines Agency has suspended the use of ulipristal acetate (UPA) in the treatment of uterine fibroids and is reassessing its association with a risk of liver injury.

Our objectives were to characterize the post-marketing reporting of drug-induced liver injury (DILI) with UPA and investigate the underlying pharmacological basis.

We queried the worldwide FDA Adverse Event Reporting System and performed a disproportionality analysis, selecting only hepatic designated medical events (DMEs) where UPA was reported as suspect. The reporting odds ratios (RORs) were calculated, and we considered a lower limit of the 95% confidence interval (LL95% CI) > 1 as significant. Physiochemical/pharmacokinetic features were extracted to assess the risk of hepatotoxicity by applying predictive DILI risk models. Mifepristone and leuprolide were selected as comparators.

A significantly higher proportion of liver disorders was reported for UPA than for mifepristone (2.9 vs. 0.8%; p < 0.00001) and leuprolide (2.9 vs. 1.6%; p = 0.015). As regards hepatic DMEs, statistically significant RORs were found for autoimmune hepatitis (N = 5; LL95% CI 16.8), DILI (n = 5; LL95% CI 5.9), and acute hepatic failure (N = 5; LL95% CI 9.3). No signals of DILI emerged for mifepristone and leuprolide acetate. UPA and mifepristone showed high lipophilicity and hepatic metabolism (predicted intermediate DILI risk). Leuprolide exhibited contrasting features, resulting in no DILI concern. Inhibition of different liver transporters and the presence of a reactive metabolite were also recognised for UPA.

Different drug properties previously linked to the occurrence of DILI may partially explain the reporting pattern observed with UPA. Our "bedside-to-bench" approach may support regulators in the risk-benefit assessment of UPA.