Effect of Hepatic Impairment on the Pharmacokinetics of a Single Dose of TD-9855

Inclusion Criteria: All Subjects: * has a body mass index (BMI) of 19 to 40 kg/m2, inclusive, and weight of at least 55 kg. * clinical labs within normal ranges * creatinine clearance of \>70 mL/min * women must be non-pregnant and non-lactating, male and females must agree to highly effective methods of contraception * additional criteria apply Subjects with Impaired Hepatic Function additional criteria: * Subject has mild (Child-Pugh Class A \[5 to 6 points\]), moderate (Child-Pugh Class B \[7 to 9 points\]), or severe (Child-Pugh Class C \[10-15 points\]) liver disease * has stable hepatic impairment defined as no clinically significant change in disease status within the last 30 days * must be on a stable dose of medication and/or treatment regimen at least 30 days before dosing * Additional inclusion criteria apply Exclusion Criteria: Subjects with normal hepatic function: * history of reactions or hypersensitivity to ampreloxetine or known intolerance to other norepinephrine reuptake inhibitors (NRI) or serotonin norepinephrine reuptake inhibitors (SNRI). * personal or family history of congenital long QT syndrome * history of untreated closed angle glaucoma * history of orthostatic hypotension or orthostatic tachycardia or a history of dizziness, lightheadedness or fainting, or a feeling of blacking out upon standing * has used nephrotoxic or hepatotoxic medications 30 days before Day-2 * routinely uses more than 2 grams of acetaminophen daily * has used tobacco-containing products (e.g., cigarettes, cigars, chewing tobacco, snuff, e cigarettes, vaporizers) within 3 months before Screening or has a positive cotinine result at Screening or Day -2 * used any CYP1A2 inhibitor or inducer within 7 days or 5 half lives, whichever is longer, prior to ampreloxetine dosing or requires concomitant use * has used monoamine oxidase inhibitors (MAO-I) within 7 days or 5 half lives, whichever is longer, prior to ampreloxetine dosing or requires concomitant use * additional exclusion criteria apply Subjects with impaired hepatic function additional criteria: * has severe ascites that could potentially interfere with respiratory function * current severe hepatic encephalopathy * history of liver transplantation, hepatocellular carcinoma, or acute liver disease * has biliary liver cirrhosis * has uncontrolled hypertension (SBP \>180 mm Hg and DBP (Diastolic blood pressure) \>110 mm Hg) * has an abnormal ECG at Screening or Day -2, including QTcF (Fridericia's corrected QT Interval) \>470 msec * additional exclusion criteria apply