Phase 3 Clinical Effect Durability of TD-9855 for Treating Symptomatic nOH in Subjects With Primary Autonomic Failure

Inclusion Criteria (For 0169 Completers Group): * Subject has completed 4 weeks of double blind treatment in Study 0169 (V6) and, in the opinion of the Investigator, could benefit from continued treatment with ampreloxetine. Only subjects with OHSA#1 score of ≤7 will be eligible for randomization for the double-blind treatment period. * Subject has a minimum of 80% study medication compliance in Study 0169. Inclusion Criteria (For De Novo Group): * Subject is male or female and at least 30 years old. * Subject must meet the diagnostic criteria of symptomatic nOH, as demonstrated by a sustained reduction in BP of ≥20 mm Hg (systolic) or ≥10 mm Hg (diastolic) within 3 min of being tilted-up ≥60o from a supine position as determined by a tilt-table test. * Subject must score at least a 4 on the OHSA#1 at V1. * For subjects with PD only: Subject has a diagnosis of PD according to the United Kingdom Parkinson's Disease Society (UKPDS) Brain Bank Criteria (1992). * For subjects with MSA only: Subject has a diagnosis of possible or probable MSA of the Parkinsonian subtype (MSA-P) or cerebellar subtype (MSA-C) according to The Gilman Criteria (2008). * For subjects with PAF only: Subject has documented impaired autonomic reflexes, including the Valsalva maneuver performed within 24 months from the date of randomization * Subject has plasma Norepinephrine (NE) levels ≥ 100 pg/mL after being in seated position for 30 minutes. Exclusion Criteria (For 0169 Completers Group): * Subje…