title: Vitamin D3 seems more appropriate than D2 to sustain adequate levels of 25OHD: a pharmacokinetic approach.
abstract: OBJECTIVE
  The superiority of cholecalciferol (D3) over ergocalciferol (D2) in sustaining serum 25-hydroxy vitamin D (25OHD) levels is controversial. To compare D2 with D3 we performed a single-blind, placebo-controlled randomized trial spanning 11 weeks.
  
  
  METHODS
  Healthy volunteers (n=33, aged 33.4±6 years) were divided into three groups (n=11, each): D2, D3 and placebo. Treatment started with a loading dose (100,000 IU) followed by 4800 IU/day (d) between d7 and d20 and follow-up until d77. Serum samples were obtained at baseline and at days 3, 7, 14, 21, 35, 49, 63 and 77.
  
  
  RESULTS
  Baseline 25OHD values in the D2 group were lower than those in the D3 and placebo groups (P<0.01). Placebo 25OHD levels never changed. As after the loading dose both D2 and D3 groups had reached similar 25OHD levels, we tested equivalence of the area under the concentration × time curve (AUC) between d7 and d77. The AUC was 28.6% higher for D3 compared with D2, and both were higher with respect to placebo. At d77, D2 25OHD levels were higher than those at baseline, but similar to placebo; both were lower than D3 (P<0.04). According to raw data, the elimination half-life of 25OHD was 84 and 111 days under D2 and D3 supplementation, respectively; after subtracting the placebo values, the corresponding figures were 33 and 82 days.
  
  
  CONCLUSIONS
  D2 and D3 were equally effective in elevating 25OHD levels after a loading dose. In the long term, D3 seems more appropriate for sustaining 25OHD, which could be relevant for classic and non-classic effects of vitamin D.
authors.affiliation: Laboratorio de Enfermedades Metabólicas Óseas, INIGEM-CONICET-UBA, Hospital de Clínicas, Buenos Aires, Argentina.
authors.forename: B
authors.initials: B
authors.lastname: Oliveri
authors.affiliation: Laboratorio de Enfermedades Metabólicas Óseas, INIGEM-CONICET-UBA, Hospital de Clínicas, Buenos Aires, Argentina.
authors.forename: S R
authors.initials: SR
authors.lastname: Mastaglia
authors.affiliation: Laboratorio de Enfermedades Metabólicas Óseas, INIGEM-CONICET-UBA, Hospital de Clínicas, Buenos Aires, Argentina.
authors.forename: G M
authors.initials: GM
authors.lastname: Brito
authors.affiliation: Laboratorio de Enfermedades Metabólicas Óseas, INIGEM-CONICET-UBA, Hospital de Clínicas, Buenos Aires, Argentina.
authors.forename: M
authors.initials: M
authors.lastname: Seijo
authors.affiliation: Segunda Cátedra de Farmacología, Facultad de Medicina, Universidad de Buenos, Buenos Aires, Argentina.
authors.forename: G A
authors.initials: GA
authors.lastname: Keller
authors.affiliation: Laboratorio de Enfermedades Metabólicas Óseas, INIGEM-CONICET-UBA, Hospital de Clínicas, Buenos Aires, Argentina.
authors.forename: J
authors.initials: J
authors.lastname: Somoza
authors.affiliation: Segunda Cátedra de Farmacología, Facultad de Medicina, Universidad de Buenos, Buenos Aires, Argentina.
authors.forename: R A
authors.initials: RA
authors.lastname: Diez
authors.affiliation: Segunda Cátedra de Farmacología, Facultad de Medicina, Universidad de Buenos, Buenos Aires, Argentina.
authors.forename: G
authors.initials: G
authors.lastname: Di Girolamo
mesh_terms: D015652:25-Hydroxyvitamin D 2 / Q000097:blood*; D000328:Adult; D001118:Argentina; D002112:Calcifediol / Q000097:blood*; D002118:Calcium / Q000097:blood / Q000652:urine; D002762:Cholecalciferol / Q000009:adverse effects / Q000378:metabolism / Q000627:therapeutic use*; D019587:Dietary Supplements / Q000009:adverse effects; D004872:Ergocalciferols / Q000009:adverse effects / Q000378:metabolism / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D006207:Half-Life; D006785:Hospitals, University; D006786:Hospitals, Urban; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D010564:Personnel, Hospital; D016037:Single-Blind Method; D014808:Vitamin D Deficiency / Q000097:blood / Q000517:prevention & control* / Q000652:urine; D055815:Young Adult
chemical_list: D004872:Ergocalciferols; D002762:Cholecalciferol; D015652:25-Hydroxyvitamin D 2; D002112:Calcifediol; D002118:Calcium