The study will comprise of three groups based on hepatic function. Participants will be screened for up to 28 days prior to investigational product (IP) administration on Day 1. Eligible participants will be admitted to the clinical unit on Day -1 and will be residential for a single period of six days/five nights. On Day 1, participants will receive a single oral dose of fezolinetant under fasting conditions followed by a 96-hour in-house blood and urine sampling period. Participants are to remain semirecumbent for four hours postdose. Standard safety and tolerability assessments will be conducted. Participants will be discharged from the clinical unit on Day 5 on the condition that all required assessments have been performed and that there are no medical reasons for a longer stay in the clinical unit.~The study will be completed with an end-of-study visit (ESV). The ESV will take place five to nine days after the last pharmacokinetic sample is collected or at the time of early discontinuation from the study.
The purpose of this study is to evaluate the pharmacokinetics of a single oral dose of fezolinetant and ES259564 (fezolinetant metabolite) in female participants with mild and moderate hepatic impairment compared to healthy female participants with normal hepatic function.~This study will also evaluate the safety and tolerability of a single oral dose of fezolinetant in female participants with mild and moderate hepatic impairment and healthy female participants with normal hepatic function.