A Study to Evaluate the Effects of ABX-1431 on Patients With Tourette Syndrome

Principal Inclusion Criteria:

- Patient is a male or female between the age of 18 and 65 years of age at the
Screening Visit.

- Patient has a diagnosis of Tourette Syndrome OR chronic motor tic disorder as
defined by the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition
(DSM-5) criteria.

- Patient's Yale Global Tic Severity Scale (YGTSS) total tic sub-scale (TTS) results
must be ≥ 18 (Range 0-50) at the Screening Visit.

- Patients taking daily medications for symptoms of Tourette Syndrome [e.g.
neuroleptics (e.g. aripiprazole, risperidone) or selective serotonin reuptake
inhibitors (e.g. fluoxetine)] must be on a stable dose of medication for at least 30
days before the Screening Visit and must be expected to remain on a stable dose
during this study.

Principal Exclusion Criteria:

- Patient is taking potent cytochrome P450 3A4/5 inducers [e.g. carbamazepine,
oxcarbazine, rifampin, St. John's Wort (Hypericum perforatum), or phenytoin].
Patient is taking strong P450 3A4/5 inhibitors including atazanavir, bocepravir,
clarithromycin, grapefruit juice, indinavir, itraconazole, ketoconazole, nefazodone,
nelfinavir, posaconazole, ritonavir, saquinavir, telithromycin, or voriconazole.

- Patients with a diagnosis of any psychiatric comorbidity (obsessive compulsive
disorder, attention deficit hyperactivity disorder) OR generalized anxiety disorder,
depression or post-traumatic stress disorder that is unstable or requires alteration
in therapy are excluded. Patients with a past history of psychosis or schizophrenia
at any time are excluded. Patients with stable OCD or ADHD requiring no alteration
in therapy may be enrolled.