A Multi-Center, Open-Label Study

Introduction Droxidopa (L-DOPS) is an orally administered, synthetic catecholamine that is
converted to the sympathetic neurotransmitter norepinephrine (NE) through a single step of
decarboxylation by the endogenous enzyme 3,4-dihydroxyphenylalanine (DOPA) decarboxylase.
Droxidopa was originally developed by Sumitomo Pharmaceuticals Co. Ltd., and has been
marketed in Japan since 1989 for the indications listed below.

- Improvement of frozen gait and dizziness on standing up in patients with Parkinson's
Disease.

- Improvement of orthostatic hypotension, syncope, and dizziness on standing up in
patients with Shy-Drager syndrome and familial amyloid polyneuropathy.

- Improvement of the following symptoms of orthostatic hypotension in patients undergoing
hemodialysis: dizziness, light-headed feeling, dizziness on standing up, malaise, and
weakness.

Chelsea hypothesizes that these indications have an deficiency or lack of activity of the
adrenergic neurotransmitter NE which can be affected by the use of a NE prodrug.

In Phase 1 clinical studies conducted in Japanese and Caucasian subjects, droxidopa was well
tolerated and no differences were noted in oral absorption between the two groups. Apart
from a moderate increase in heart rate in one Caucasian subject (receiving 600 mg
droxidopa), which was considered to be possibly related to study medication, there were no
other adverse events (AEs) that were considered to be related to droxidopa treatment. The
maximum plasma concentration (Cmax) was reached between 2 and 3 hours after single, oral
doses of droxidopa (100 to 900 mg). The plasma elimination half-life (t½) of droxidopa was
1.4 - 1.5 hours and approximately 15% of the drug was recovered unchanged in the urine. No
drug accumulation was observed after multiple oral dosing with droxidopa (300 mg twice daily
for 5 days).

Although the therapeutic effects of droxidopa are believed to be due to the conversion of
droxidopa to NE, the major metabolite of droxidopa is methylated droxidopa (3-OM-DOPS).

After administration of single 100 mg and 300 mg doses to healthy volunteers, droxidopa,
3-OM-DOPS, and NE were observed in the urine. The 24-hour excretions of droxidopa and
3-OM-DOPS accounted for approximately 15% and 8% of the administered dose (3-OM-DOPS
uncorrected for molecular weight), suggesting that renal function may impact the clearance
of droxidopa and 3-OM-DOPS.1,2 A population PK study conducted in patients with Primary
Autonomic Failure indicated that increasing age was associated with decreased clearance of
both droxidopa and 3 OM DOPS (Apparent clearance decreased 0.8% per year of age [referenced
to age 65 years]). Further it was identified that patient's concurrently taking L-Dopa or
dopamine derivatives had approximately 50% of the clearance seen with patients not taking
droxidopa. 6 From a safety perspective, droxidopa has been generally very well-tolerated
across a large variety of patient populations.

As a precursor of NE that can be administered orally, droxidopa is expected to provide a
therapy for NOH in patients with autonomic failure associated with neurodegenerative
diseases.

The Investigator's Brochure3 should be reviewed for a complete description of the non
clinical and clinical experience with droxidopa.

2.0 Objectives 2.1 Primary Objective The primary objective of this study is to evaluate the
pharmacokinetics (PK) of droxidopa in subjects with mild, moderate, and severe renal
dysfunction and ESRD after a single oral dose compared to matched healthy subjects with
normal renal function.

The PK parameters Cmax, Tmax, AUC(inf), CL/F, Vz/F, t½, and CLr are considered the primary
parameters for evaluation.

2.2 Secondary Objective The secondary objective of this study is to assess the safety and
tolerability of Droxidopa in matched healthy subjects and those with mild to severe renal
dysfunction and ESRD through participant AEs and laboratory measures.

3.0 Investigational Plan 3.1 Study Description This study will be an open-label,
single-treatment, single-dose, parallel group study to evaluate the PK of droxidopa in
subjects with mild, moderate, and severe renal dysfunction and ESRD after a single dose
compared to matched healthy subjects with normal renal function.

Inclusion Criteria:

- Informed Consent

- Male or Female between 18 and 79 years

- Female subject of childbearing potential not surgically sterile or min 2 years
postmenopausal must use approved contraceptives

- BMI 20 to 40 kg per m2

- Refrain from exercise

- eGFR per protocol for condition

- Sufficient venous access

- Stable medication dosing 14 days prior to and during study

- Healthy control subjects must show good general health per protocol

- Subjects will be matched Healthy to Renal Impaired by demographics data

Exclusion Criteria:

- Inability to complete study

- Insufficient venous access

- Clinically significant illness within 4 weeks of study

- History of clinically unstable disease except renal impairment in those subjects

- Medical or surgical conditions that may inhibit absorption of IP

- Laboratory value or medical issue which may interfere with study data or be hazardous
for the subject

- Medication that may interfere with drug absorption or elimination process 4 weeks
prior to study

- Consumption of grapefruit products within 7 days prior and after study

- Dose changes of medications 14 days prior to and during study

- Active alcohol abuse or drug addiction

- Positive alcohol test at screening or after

- Excessive xanthine consumption

- Positive serology test Hepatitis B or Hepatitis C or HIV

- Excessive nicotine usage

- Positive urine screen for drugs of abuse without prescription

- Clinically relevant abnormal 12 lead ECG

- Donation of bood or plasma or platelets within 30 days of study

- Clinical trial with another agent within 30 days or 5 half lives whichever is longer

- Informed consent unavailable or withdrawn

- Any condition the investigator feels would interfere with study data or subjects
health

- Employee or relative of study center or center staff or investigator

- Any condition that may increase risk for subject

- Clinically significant lab value

- Clinically significant acute or chronic disease other than renal impairment in those
subjects that may interfere with data or health

- Medication dose change within 14 days of study

- Seated BP greater than 180 over 105

- Healthy subject with history of renal impairment