A Study to Investigate the Effect of Hepatic Impairment on the Pharmacokinetics and Safety and Tolerability of a Single Oral Dose of Risdiplam Compared to Matched Healthy Participants With Normal Hepatic Function

This is a multi-center, open-label, non-randomized, parallel-group, 2-part study to evaluate the effect of hepatic impairment on the PK and safety and tolerability of a single oral dose of risdiplam compared to matched healthy participants with normal hepatic function.


Eligibility Criteria:
Inclusion Criteria:

All Participants:

* BMI between 18.0 and 36.0 kilograms per square metre (kg/m2), inclusive, and body weight \> / = 50 kg
* Females must not be pregnant or lactating and must be of non-childbearing potential
* Male participants (whether surgically sterilized or not) with female partners of childbearing potential must use methods of contraception from Screening until 4 months after their dose of the study drug as detailed in the protocol
* Male participants must not donate sperm from Check-in (Day -1) until 4 months after their dose of the study drug

Participants with Normal Hepatic Function Only:

* Matched to participants with mild or moderate hepatic function in sex, age, BMI, and smoking status
* In good health, as determined by no clinically significant findings from medical history, physical examination, 12-lead ECG, vital sign measurements, and clinical laboratory evaluations

Participants with Hepatic Impairment Only:

* Documented chronic stable liver disease
* Currently on a stable medication regimen, defined as not starting new drug(s) or changing drug dose(s) within 3 months of administration of study drug
* Anemia secondary to hepatic disease will be acceptable, if hemoglobin \>/= 9 gram per decilitre (g/dL). Participants must have a platelet count \</= 35 000 platelets

Exclusion Criteria:

All Participants

* Significant history or clinical manifestation of any metabolic, allergic, dermatological, renal, hematological, pulmonary, cardiovascular, gastrointestinal, neurological, respiratory, endocrine, or psychiatric disorder
* History of significant hypersensitivity, intolerance, or allergy to any drug compound, constituents or excipients of the study drug, food, or other substance
* History of stomach or intestinal surgery or resection that would potentially alter absorption and/or excretion of orally administered
* Ventricular dysfunction or history of risk factors for Torsades de Pointes
* Evidence of hepatorenal syndrome and estimated creatinine clearance range \< 60 millilitre per minute (mL/min) or abnormal sodium and potassium levels
* Clinically significant physical examination abnormality
* History of diabetes mellitus
* Use or intend to use any medications/products known to alter drug absorption, metabolism, or elimination processes, including St. John's Wort
* Positive human immunodeficiency virus (HIV) test
* Participation in a clinical study involving administration of an investigational drug prior to dosing
* Smoke more than 10 cigarettes or use the equivalent tobacco- or nicotine-containing products per day
* Receipt of blood products within 2 months prior to study
* Donation of blood, plasma, or platelets prior to Screening
* Poor peripheral venous access
* Have previously completed or withdrawn from this study or any other study investigating risdiplam, and have previously received the investigational product

Participants with Normal Hepatic Function Only:

* Confirmed supine blood pressure \> 150 millimetre of mercury (mmHg) or \< 90 mmHg
* Positive test for hepatitis B or C virus
* Clinically significant abnormal laboratory values
* Significant history or clinical manifestation of hepatic disorder
* History or presence of liver disease or liver injury
* Use or intend to use any prescription medications/products within 14 days prior to dosing

  -. Use or intend to use slow-release medications/products considered to still be active within 14 days prior to dosing
* Use or intend to use any non-prescription medications/products within 7 days prior to dosing

Participants with Hepatic Impairment Only:

* Confirmed supine blood pressure \> 159 mmHg or \< 90 mmHg
* Values outside the normal range for liver function tests that are not consistent with their hepatic condition
* Use of a new medication, or a change in dose, for the treatment, or worsening of, hepatic encephalopathy
* Use of prescription drugs within 14 days of study drug administration
* Recent history of, or the treatment of, esophageal bleeding
* Presence of a portosystemic shunt
* Recent history of paracentesis
* Current functioning organ transplant or are waiting for an organ transplant
* Evidence of severe ascites
* History or current symptoms of hepatic encephalopathy Grade 2 or above