Similar Vitamin D2 and D3 pharmacokinetics with a single and daily doses

MASTAGLIA SILVINA ; SEIJO MARIANA ; BRITO GRACIELA ; KELLER GUILLERMO ; SOMOZA JULIA ; DIEZ ROBERTO ; DIGIROLAMO GUILLERMO ; OLIVERI BEATRIZ

San Diego, California

Congreso; ASBMR 2011 Annual Meeting; 2011

The American Society for Bone and Mineral Research

Some studies found cholecalciferol (D3) to be superior to ergocalciferol (D2) based on the effect of increasing or maintaining serum 25-hidroxyvitamin-D (25OHD) levels. However, others reported both calciferols to be equivalent. The aim of this study was to clarify and compare the pharmacokinetics of D2 and D3. We carried out a single-blind; placebo-controlled randomized trial during 11 weeks (September to December 2010) in Buenos Aires city (34ºS). Thirty-three young healthy volunteers (7M/ 26F) with an age of (mean±SD) 33.4±6 years and BMI 22.6±2 Kg/m2 were included. The subjects were divided in groups: D2 (n=11); D3 (n=11) and placebo (n=11). In the D groups the subjects received at the start a single dose of 100,000IU and 4,800 IU/day (d) of the vitamin D allocated from 7 to 21 d. No vitamin D was administrated from 22 to 77 d. The serum samples were obtained at basal and d: 3, 7, 14, 21, 35, 49, 63 and 77 to measure sCa, sP, iPTH, BAP, 25OHD (RIA-DIASORIN) and 2 hours urinary uCa/uCr ratio. Baseline 25OHD (ng/ml) levels were: D2: 16.3±7; D3: 24.2±6 (p<0.01) and placebo: 22.6±7. No differences were observed in the other biochemical parameters whereas placebo values of 25OHD did not increase over treatment, vitamin D administration augmented serum 25OHD levels in each sampling point, as shown in figure 1. To take into account variability in basal 25OHD serum levels, subtraction of basal values was performed before pharmacokinetic analysis. For D3-treated subjects, AUC was 1107±481 ng.d.ml-1 (range 331-1920, 95%CI 823-1391), ke -0.246±0.104 day-1 (range: -0.479 to -0.125, 95%CI -0.307 to -0.185) and t½ 3.267±1.274 days (range 1.448-5.545, 95%CI 2.514-4.020). For D2-treated subjects AUC was 1005±352 ng.d.ml-1 (range 638-1784, 95%CI 797-1213), ke -0.321±0.245 day-1 (range: -0.911 to -0.107, 95%CI -0.466 to -0.176) and t½ 3.105±1.658 days (range 0.761-6.469, 95%CI 2.124-4.085). Under this administration scheme, no pharmacokinetic differences were found between the two treatments. Conclusion: under the experimental conditions selected, vitamin D2 was equally effective as vitamin D3 in raising and maintaining 25OHD and levels.