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): 18.0-999.0,  Healthy Is the individual a healthy, normal adult man and woman who volunteers to participate? ls s/he at least 18 years of age? Is his/her BMI between 19 and 30, inclusive? Is she willing .to avoid pregnancy by abstaining from sexual intercourse with a non-sterile male partner, or by the use one of the following methods: diaphragm + spermicide or condom + spermicide (at least 14 days before dosing), intra uterine contraceptive device or hormonal contraceptives (at least 4 weeks prior to dosing), or has she been surgically sterile or post-menopausal at least six months prior to entering into the stndy? Is s/he considered .reliable and capable of understanding his/her responsibility and role in the study Has s/he provided written informed consent? A no answer to any of the above questions indicated that the individual was ineligible for enrollment  Does the individual have a history of allergy or hypersensitivity to amlodipine? Does s/he have clinically significant laboratory abnormalities that would interfere with the conduct or interpretation of the study or jeopardize his/her safety? Does s/he have significant history or clinical evidence of auto-immune, cardiovascular, gastrointestinal, hematological, hematopoietic, hepatic, neurological, ongoing infection, pancreatic, or renal diseases that would interfere with the conduct or interpretation of the study or jeopardize his/her safety'? Is she nursing? Does s/he have serious psychological illness? Does s/he have significant h/story (within the past year) or clinical evidence of alcohol or drug abuse? • Does s/he have a positive urine drug screen or a positive HIV-1, or hepatitis B or C screen, or a positive pregnancy test? Has s/he consumed grapefruit or grapefruit juice during the 7rday period preceding study initiation? Is s/he unable to refrain from the use of alcohol or xanthine-containing foods or beverages during periods beginning 48 hours prior to study drug administration and ending when the last blood sample has been taken in each study period? Has s/he used any prescription drug, other than hormonal contraceptives, during the 14-day period prior to study initiation, or any OTC drug during the 72-hour period preceding study initiation? Is s/he unable to refrain from the use of all concomitant medications, other than hormonal contraceptives, during the study? Has s/he donated or lost blood, or participated in a clinical study which involved the withdrawal of a large volume of blood (480 mL or more), during the six week period preceding study initiation? Has s/he donated plasma during the two week period preceding study initiation? Has s/he received an investigational drug during the 30 day period preceding study initiation? Is s/he a heavy smoker (usually smoking more than 10 cigarettes per day)?