Pharmacokinetics of Vitamin D in Multiple Sclerosis Patients and Healthy Controls. (P3.192)

OBJECTIVE: To determine if oral vitamin D supplementation in MS patients and healthy controls leads to a similar increase in serum 25-hydroxyvitamin D levels. BACKGROUND: Vitamin D insufficiency, a risk factor for multiple sclerosis (MS), is also associated with increased inflammatory activity in established MS. Since vitamin D insufficiency is common in the general population and genes associated with vitamin D metabolism have been linked to MS susceptibility, we hypothesized that vitamin D metabolism may differ in patients with MS compared to healthy individuals. DESIGN/METHODS: Participants in this open-label pilot study were female, white, aged 18-60 years, had 25-hydroxyvitamin D levels ≤ 30 ng/mL at screening, and had relapsing-remitting MS or were healthy controls. Subjects received 5,000 IU (125 µg)/day of oral cholecalciferol (vitamin D3) supplementation for 90 days. The primary outcome variable was the change in mean serum level of 25-hydroxyvitamin D level. The primary predictor was disease status (MS versus control). A sample size of 24 in each group was calculated to detect a 10% difference in change in vitamin D levels between the two groups, with a two-sided alpha of 0.05 and a power of 90%. RESULTS: 22 subjects with relapsing-remitting MS seen at the UCSF or Johns Hopkins MS Center and 30 healthy controls have been enrolled to date. The study will be completed by March, 2014. The mean age of subjects was 41.4 ± 11.1 years, and the mean screening 25-hydroxyvitamin D level was 23 ± 5.92 ng/mL in MS patients and 22.5 ± 5.88 ng/mL in controls. There were no significant group differences in baseline demographic characteristics. There have been no significant adverse events to date. CONCLUSIONS: High-dose vitamin D3 supplementation appears to be safe and well-tolerated. The results for the primary endpoint (change in 25-hydroxyvitamin D level) will be presented. Study Supported by: NIH NINDS K23 067055 to EMM. Disclosure: Dr. Steele has nothing to disclose. Dr. Bhargava has nothing to disclose. Dr. Marcus has received personal compensation for activities with Biogen Idec. Dr. Marcus has received research support from Biogen Idec. Dr. Revirajan has nothing to disclose. Dr. Waubant has received personal compensation for activities with Roche Diagnostics Corporation, Biogen Idec, Sanofi-Aventis Pharmaceuticals Inc., Genzyme Corporation, and Novartis. Dr. Mowry has received research support from Teva Neuroscience.