Increase in the number of centers participating from 10 to 15. Eliminate weight restriction enrollment criteria. Increase the screening period from 1 week to 21 days.

Protocol template language updated to current SOP protocol template. Increase in the number of centers participating from 15 to 60. Removal of exclusion of subjects with prior treatment with pregabalin. Exclusion of subjects with history of pregabalin intolerance and subjects with a history of intolerability to pregabalin, or with a history of insufficient response in the treatment of epilepsy. Change of concomitant medication exclusion from exclusion of CNS active medications to exclusion of psychotropic compounds. Addition of safety assessments using the Sheehan-Suicidality Tracking Scale and the Patient Health Questionnaire-8.

To add new safety wording. To allow for rescreening of subjects. To add clarification around the timing of the visual field testing (VFT) and handling of the primary endpoint as an AE. Also clarification of prohibited and allowed concomitant medications; and documentation of adverse events related to changes from entry in vital signs, weight and on the physical exam. PASS language added, Subject Selection, Compliance, DMC text added.

Single Reference Safety Document (SRSD) for this study was changed from the Core Data Sheet (CDS) to the Investigators Brochure (IB). The following changes were made to comply with FDA and Neuropsychiatric and Abuse Potential Advisory Council (NAPAC) Guidance: • Suicidality assessment: the Columbia-Suicide Severity Rating Scale (C-SSRS) will be performed instead of the Sheehan-Suicidality Tracking Scale (S-STS) for subjects screened following approval/initiation of Amendment 4. Subjects who are randomized under Amendment 3 will not switch to the C-SSRS. • Suicidal Behaviors Questionnaire–Revised (SBQ-R) will be performed at screening. • Scoring instructions for the PHQ8 have been inserted as well as a reference to the Instruction Manual. The following protocol exclusion has been inserted to increase subject safety: • Any subject at risk of suicide or self-harm based on investigator judgment and/or details of a mental health risk assessment (MHRA) by a qualified mental health professional. • The number of sites to participate in the study has been deleted. The following changes were made to comply with the current protocol template and required language/wording: • Abbreviation list moved to an Appendix. • Updated terms study drug and study medication to investigational product for • consistency. • Inserted Lifestyle Guidelines which includes template contraception language. • Inserted Sponsors Medically Qualified Personnel. • Updated Trial Treatments including insertion of new sections for Investigational Product Storage, Investigational Product Accountability and Destruction of • Investigational Product Supplies. • Updated Drug Supplies. • Updated Investigational Product Storage. • Updated Quality Control and Quality Assurance. • Inserted Medication Errors. • Updated Exposure During Pregnancy. • Inserted Occupational Exposure. • Updated Publication of Results.