Pharmacokinetic Study: Effect of 25(OH)D and Vitamin D3 on Serum 25(OH)D

Pharmacokinetic Study in Healthy Postmenopausal Women to Compare Supplementation of Vitamin D3 to 25(OH)D

We compare the effect of HyD (25-hydroxyvitamin D) and vitamin D3 in their effect on 25-hydroxyvitamin D plasma levels over a course of 4 month. This is a pharmacokinetic study including 35 postmenopausal women.

• Trial with medicinal product

We include postmenopausal women age 50 to 75, race/ethnicity: Caucasian, serum 25(OH)D at baseline between 20 to 60 nmol/l, body mass index: < 30 kg/m2

to compare 25(OH)D and vitamin D3 in equimolar doses over a 4 month pharmacokinetic trial. The dosing arms are daily, weekly, and bolus

Inclusion criteria:

• Postmenopausal women
• Age 50 to 75 years
• Body mass index 18-29 kg/m2
• 25-hydroxyvitamin D levels 20 to 60 nmol/l
• Caucasian
• Generally healthy

Exclusion criteria:

• Serum calcium > 2.6 nmol/L
• Use if dietary supplements (> 400 IU vitamin D per day, > 600 mg of calcium per day)
• Hypertension
• Diseases that carry the risk of hypercalcemia
• Use of any drug that interferes with bone metabolism in the last 12 months (bisphosphonates estrogen receptor modulators, PTH, calcitonin)
• Oral HRT in the last 6 months
• Extreme diets
• Fracture or fall in the last 3 months
• Current smoking or alcohol abuse
• Planning on a sunny vacation in the course of the trial
• Kidney stone history
• Creatinine clearance < 30 ml/min
• Co-medications: anticoagulants, PTH, corticosteroids, thiazide diuretics, digoxin, anticonvulsants, malabsorption,z C