Effect of an Inhibitor of Cholesterol Absorption on Vitamin D Levels

Objectives: To evaluate the serum levels of 25(OH)D after a single oral dose of cholecalciferol 50,000 IU plus ezetimibe or placebo.

Experimental design: Double-blind randomized controlled trial. Research location: Porto Alegre Clinical Hospital (HCPA), RS, Brazil. Participants: Medical residents of the HCPA. Intervention: The groups will be randomized to ezetimibe 10 mg for 5 days or placebo. On the fifth day, they should came after an overnight fast for blood tests collection [25(OH)D, PTH, calcium, albumin]. Next, all participants will receive orally a cholecalciferol 50,000 IU capsule and a snack containing 15g of fat. Participants will return 14 days after that for a second blood test.

Statistical Analysis: Paired samples t-test or Wilcoxon signed rank-test will be used for comparing variables in two distinct moments (before cholecalciferol and 14 days after). The correlation between the numerical variables will be evaluated by the Spearman's correlation coefficient. A p value of less than 0.05 was considered statistically significant.

Expected results: Differences between the serum levels of 25(OH)D in response to cholecalciferol plus ezetimibe compared to cholecalciferol plus placebo.

Cost/benefit of the project: This is a low budget and minimal risks study that will contribute to a better understanding of the absorptive process of vitamin D and the effect of ezetimibe on its absorption.

Inclusion criteria

• Medical students of the HCPA

Exclusion criteria

• Body mass index >+ 25 or < 18.5 kg/m2
• Known liver, kidney or endocrine disease
• Known malabsorption
• Use of supplements of calcium and/or vitamin Danticonvulsants, barbiturates, or glucocorticoids
• Travel outside the Brazilian south region during the previous 120 days