Study to Investigate the Influence of Hepatic Insufficiency on the Pharmacokinetics of Tozadenant

• Tozadenant (Drug): Two 60 mg tablets for a total single study dose of 120 mg

Primary outcomes

• To evaluate the pharmacokinetics (PK) [area under the time-concentration curve] of a single-dose of tozadenant in subjects with hepatic impairment to healthy subjects. [up to 12 days]: To evaluate the pharmacokinetics (PK) \[area under the time-concentration curve\] of a single-dose of tozadenant in subjects with hepatic impairment compared to the PK of a single-dose of tozadenant in healthy subjects.

Secondary outcomes

• Subjects with hepatic impairment will be evaluated for safety assessments (adverse events and treatment-related adverse events) by physical examinations. [up to 12 days]: To evaluate the safety and tolerability of a single-dose of tozadenant in subjects with hepatic impairment by physical examinations, vital sign measurements and Columbia-Suicide Severity Rating Scale (C-SSRS) questionnaire.

Sex: All, ages: 18 Years to any, accepts healthy volunteers

Inclusion Criteria:

All subjects must fulfill the following to participate:

* Subject has given his/her written informed consent on an IEC or IRB approved consent form.
* Subject understands the study procedures in the informed consent form (ICF), and is willing and able to comply with the protocol.
* Be either male or female 18 years old
* Have a BMI ≥ 18.5 and ≤ 40.0 kg/m2 at screening
* Is a continuous non-smoker or a smoker who will consume up to 10 cigarettes/day
* Child bearing females should be sexually inactive (abstinent) prior to dosing
* Females subjects of non childbearing potential must have undergone one of the following sterilization or be postmenopausal

Subjects with mild, moderate, or severe hepatic impairment must:

* Have a medical history consistent with a diagnosis of hepatic impairment.
* Have a diagnosis of chronic (> 6 months), stable hepatic insufficiency

Healthy subjects must be:

* Medically healthy with no significant medical history

Exclusion Criteria:

Subjects must not be enrolled in the study if they:

* Previously participated in any study with tozadenant
* Has orthostatic hypotension, history or symptoms of cardiovascular disease, or hypertensive crisis.
* Currently participating in or has participated in another study and received drug (active or placebo)
* Have a known diagnosis of malignant melanoma
* Have a current episode of major depression
* Has a recent history of suicide attempt
* Has any other condition or clinically significant abnormal findings on the physical or neurological examination, psychiatric and medical history
* Had surgery or any medical condition within 6 months
* Unable to refrain from or anticipates the use of any drugs, vitamins, natural or herbal supplements
* Subject is currently lactating or pregnant or planning to become pregnant.
* Recent donation of blood, plasma or significant blood loss
* Has positive test for ethanol or drugs of abuse or a history of chronic alcohol or drug abuse
* Clinically significant medical history
* Positive results hepatitis B surface antigen (HBsAg) or hepatitis C virus (HCV) for Healthy Volunteers only.

• Richard Preston, MD, Principal investigator, University of Miami