Pharmacokinetics of Vitamin D in Multiple Sclerosis and in Health

Inclusion Criteria:

- Female

- Healthy or multiple sclerosis

- Aged 18 to 60

- Body mass index is between 18 kg/m2 and 30 kg/m2

- Screening 25-hydroxyvitamin D level ≤ 75 nmol/L (30 ng/mL)

- White race

- Non-Hispanic ethnicity

- Willing to use birth control during study

- Willing to not use tanning bed during study

If subject has multiple sclerosis:

- Relapsing-remitting MS, as defined by McDonald 2005 criteria

- Screening Expanded Disability Status Scale score ≤ 3.0

- Using no medication for MS, or taking Copaxone, (glatiramer acetate), interferons, or
natalizumab

Exclusion Criteria:

- Pregnant or nursing

- Taking multivitamin & unwilling to remain off it during study

- Taking cod liver oil & unwilling to remain off it during study

- On a fat-restricted diet

- History of renal disease or nephrolithiasis (kidney stones)

- History of liver disease

- Taking thiazide diuretics

- History of hyperthyroidism

- History of infection with Mycobacterium species

- History of sarcoidosis

- History of cancer

- History of cardiac disease

- History of HIV

- History of gastrointestinal disorder

- Taking medications that interfere with gastrointestinal absorption

- Cigarette smoker in past month

- Use of illicit drugs in past month

- Use of steroids in past month

- History of hypercalcemia, and screening serum calcium ≤ 10 mg/dL (UCSF) or ≤ 10.7
mg/dL (Johns Hopkins)

- History of hypercalciuria

- Evidence of anemia (Hgb <11.0 g/dL)

- History of other serious medical conditions

- Taking medications that involve the P450 system or may interact with vitamin D
(digoxin, diltiazem, verapamil, cimetidine, heparin, or low-molecular weight heparin)

- Other concerns about safety from the perspective of the treating physician

If subject has MS:

-History of major heat sensitivity (leading to sun-avoidant behaviors)