Patient description: The patient is a 35-year-old woman with myasthenia gravis, class IIa. She complains of diplopia and fatigue and weakness that affects mainly her upper limbs. She had a positive anti-AChR antibody test, and her single fiber electromyography (SFEMG) was positive. She takes pyridostigmine 60 mg three times a day. But she still has some symptoms that interfere with her job. She is a research coordinator and has 3 children. Her 70-year-old father has hypertension. She does not smoke or use illicit drugs. She drinks alcohol occasionally at social events. Her physical exam and lab studies were not remarkable for any other abnormalities. BP: 110/75 Hgb: 11 g/dl WBC: 8000 /mm3 Plt: 300000 /ml Creatinine: 0.5 mg/dl BUN: 10 mg/dl Beta hcg: negative for pregnancy

Clinical trial eligibility criteria: eligible ages (years): 18.0-55.0,  Multiple Sclerosis, Relapsing-Remitting Multiple Sclerosis MS as defined by the 2010 Revised McDonald MS Diagnostic (19) Age 18-55, inclusive, at the time of the first screening baseline visit EDSS 1.0 to 6, inclusive, at the time of the first screening baseline visit Able to provide informed consent Willing and able to participate in all aspects of trial design and follow-up Undergoing treatment with glatiramer acetate for a period of at least 1 year prior to enrollment in the study For female patients, agreeing to commit to the use of a reliable/accepted method of birth control (i.e. hormonal contraception, including birth control pills, injected hormones, and vaginal ring; intrauterine device; barrier methods with spermicide, including diaphragm and condom; or surgical sterilization, including hysterectomy, tubal ligation, and vasectomy) for the duration of the study FOR MS -Development of new T2 hyperintense or contrast enhancing lesions by MRI during the screening phase, but 3 such lesions on any single scan  Alternative diagnoses that better explain neurological disability and MRI findings Clinically significant medical condition that, in the best judgment of the investigators, may expose the patient to undue risk of harm or prevent the patient from completing the study (examples but are not limited to, cerebrovascular disease, substance abuse, ischemic cardiomyopathy, clotting disorder, brittle diabetes, neurodegenerative disorder) Undergoing treatment with medications that may interact with guanabenz, including anti-hypertensive agents and/or agents leading to increase in catecholamines (such as tricyclic antidepressants and monoamine oxidase inhibitors) Medical contraindication to MRI Determination, in the best judgment of the investigators, of the need to treat a prospective participant with steroids for management of MS during the screening period Pregnant or breastfeeding woman Abnormal screening/baseline blood tests exceeding any of the limits defined below: A) Serum alanine transaminase or aspartate transaminase levels greater than 3 times the upper limit of normal values B) Total white blood cell count < 3000/mm3 C) Platelet count < 85000/mm3 D) Serum creatinine level > 2.0 mg/dl and eGFR (estimated glomerular filtration rate) < 60 FOR MS Evidence of 1 or more clearly documented MS relapses within the last 1 year Development of more than 2 lesions per year relative to an MRI performed at least one year before the first screening MRI (the prior MRI can be an outside MRI)