Inclusion Criteria:  Male or female adult (aged 18-65) with Tourette Syndrome according to Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V). Total Tic Score (TTS) ≥ 20 on the Yale Global Tic Severity Scale (YGTSS) at screening and baseline. In investigator's opinion the presenting tic symptoms cause at least a moderate degree of distress or impairment. On stable psychiatric medication regimen for a minimum of 4 weeks prior to beginning the trial including medications thought to effect tic symptoms. Females of childbearing potential had a negative pregnancy test, must agree to practiced acceptable double-barrier methods of contraception (or abstinence), and were not pregnant or lactating. Willing to participate voluntarily and sign a written informed consent form. In the opinion of the investigator, the subject is considered likely to comply with the study protocol and to have a high probability of completing the study.  Exclusion Criteria:  Medical history consistent with another neurologic condition that may have had accompanying abnormal movements (e.g., Huntington's disease, Parkinson's disease, Sydenham's chorea, Wilson's disease, Mental retardation, Traumatic brain injury, Stroke, Restless legs syndrome); History of schizophrenia, bipolar disorder, or other psychotic disorder; intellectual disability or Autism Spectrum Disorder (Level 2 or 3 functioning - requiring substantial social supports or more); Recent change (less than 4 weeks) in medications that have potential effects on tic severity (such as alpha-2 agonists (guanfacine, clonidine or prazosin), SSRIs, clomipramine, naltrexone, lithium, anxiolytics, topiramate, baclofen, VMAT2 inhibitors, ecopipam or compounds containing delta-9 tetrahydrocannabinol (delta-9-THC) or cannabidiol). Medication change is defined to include dose changes or medication discontinuation. Recent change in behavioral treatment for Tourette syndrome or comorbid conditions (i.e. OCD) within the last 4 weeks or initiation of behavioral therapy for tics within the last 12 weeks. Sexually active males or females who would not commit to utilizing 2 of the approved birth control methods or who would not remain abstinent during the trial and for 90 days (males) or 30 days (females) following the last dose of IP Significant psychoactive substance use disorder within the past 3 months; or the urine drug screen was positive for cocaine, opiates, amphetamines, benzodiazepines or marijuana. Subjects prescribed stable medications that cause positive drug tests e.g. benzodiazepines, dronabinol or psychostimulants will be included as long as they do not test positive for substances unexplained by their prescription medication.  Significant lab abnormality:  Platelets ≤ 75,000/mm3 Hemoglobin ≤ 9 g/dl Neutrophils, absolute ≤ 1000/mm3 Aspartate transaminase (AST) > 3×ULN (upper limit of normal) Alanine aminotransferase (ALT) > 3×ULN Creatinine ≥ 2 mg/dl History or presence of any clinically important medical condition that, in the judgment of the investigator, is likely to deteriorate, could be detrimental to the subject, or could affect the subject's ability to complete the study.