Zonisamide Outpatient Study

Inclusion Criteria: 1. Be willing and able to sign and date an informed consent form 2. Be a military service member or Veteran 3. Male or female, 18-55 years of age 4. Meet Diagnostic and Statistical Manual (DSM)-5 criteria for AUD 5. Meet the DSM-5 diagnostic criteria for PTSD; PTSD diagnosis and severity will be determined based on CAPS-5 score greater than or equal to 33 6. Self-report drinking heavily (5 standard units for males, 4 for females) on at least 30% of the 42 days prior to the screening interview 7. Score less than 10 on the revised clinical institute withdrawal assessment for alcohol scale (CIWA-Ar) assessed in the context of a breath alcohol concentration (BAC) less than or equal to 0.02% to demonstrate that they do not need medical detoxification (Sullivan et al. 1989) 8. Have blood lab tests assessed at screening with ranges falling within the acceptable limits as noted in the protocol. 9. Have normal vitals (heart rate 60-100 bpm, systolic blood pressure 90-140 mmHg and diastolic blood pressure 60-90 mmHg) and a baseline ECG that demonstrates clinically normal sinus rhythm, clinically normal conduction, normal QTc, and no clinically significant arrhythmias. Note that clinical judgement will be used when characterizing bradycardia among some healthy subject populations, for example, conditioned veterans. Thus, some individuals with bradycardia (i.e., heart rate less than 60 bpm) may be enrolled as determined by the admitting physician. 10. Have a self-reported medical history and brief physical examination demonstrating no clinically significant contraindications for study participation, in the judgment of the admitting physician 11. Psychotropic medication free (with exception of SSRIs/SNRIs) for 7 or more days (or longer, depending on medication half-life) prior to enrollment 12. Be willing/able to stop use of any sleep medication for the duration of the study 13. Be willing to comply with all study procedures and be available for the duration of the study 14. Women must either be unable to conceive (i.e., surgically sterilized, sterile, or post-menopausal) or using double-mode form of contraception (i.e. barrier plus, e.g., birth control pills + intrauterine device, condoms + spermicide, etc.). Women can be receiving hormone replacement treatment (HRT) if the HRT dose has been stable for a period of at least 3 months 15. Women must provide negative urine pregnancy tests prior to randomization 16. Be willing to undergo a hearing test and be able to detect 500-2000 Hz tones at 40 dB or less. Exclusion Criteria: 1. DSM-5 criteria for substance use disorders other than alcohol or nicotine or test positive for prescription or illegal drugs. Regarding marijuana/THC, an individual must test negative at the screening. If an individual's test is positive, they will be given a grace period where they will have the opportunity to return and test negative prior to being enrolled. 2. Be pregnant or nursing 3. Be taking blood pressure medications, psychotropics (with exception of SSRIs/SNRIs), drugs effecting the CNS, medications contraindicated with ethanol, any sulfonamide, or any other medication that could interact with study medications or alter the effects of alcohol. a. Note that participants may currently be seeking treatment (or already receiving a behavioral treatment) for AUD, but may not be taking medications used in the treatment of AUD (acamprosate, disulfiram, oral naltrexone, and extended-release injectable naltrexone, and topiramate) 4. Have neurological or psychiatric disorders other than PTSD or AUD (except mild/moderate depression succeeding PTSD). Examples include: 1. Current psychosis, bipolar illness or major depression requiring treatment. 2. Organic brain disease or dementia assessed clinical interview. 3. History of any psychiatric disorder which would require ongoing treatment or which would make study compliance difficult. 4. History of suicide attempts within the past year and/or current suicidal ideation/plan 5. Have evidence of untreated or unstable medical illness including: cardiovascular, neuroendocrine, autoimmune, renal, hepatic, or active HIV+, AIDS infection. 6. Have a history of medically adverse reactions to alcohol (e.g., loss of consciousness, chest pain, or epileptic seizure) or major alcohol-related medical complications requiring hospitalization (i.e. hepatitis or pancreatitis) 7. Have contraindication(s) to take the study medications such as renal or hepatic impairment, congenital metabolic disorders, or hypersensitivity/allergies to study drug or similar compounds 8. Have current epilepsy or evidence suggestive of seizure disorder 9. Have past brain injury/head trauma with current symptoms (e.g. not photophobic, dizziness, etc.) or past report of loss of consciousness (LOC) for greater than 30 minutes and/or have been blast-exposed or had LOC of greater than 1 minute and current post-concussive symptoms 10. Self-report more than thirty days abstinence from alcohol during the three months prior to enrollment/consent 11. Current signs of violence or aggression, assessed as part of the consent process 12. Participation in a pharmaceutical trial or exposure to any investigational drugs within 1 month of the screening visit 13. Hearing loss that would interfere with the FPS measures 14. Have any other illness, condition, or use medications (psychotropic or antiretroviral), which in the opinion of the PI and/or the admitting physician would preclude safe and/or successful completion of the study