Pharmacokinetics of a single, large dose of cholecalciferol.
BACKGROUND
There is much interest in dosing vitamin D intermittently for patient convenience and long-term adherence.


OBJECTIVE
The objective was to characterize the time course and response of 25-hydroxyvitamin D (calcidiol) to a large oral dose of cholecalciferol.


METHODS
One group (30 subjects) was supplemented with a single oral dose of 100,000 IU cholecalciferol. A second group (10 subjects) served as a control group to assess the seasonal change of calcidiol. Serum calcidiol concentrations were followed for 4 mo. The subjects were healthy with limited sun exposure (<10 h/wk) and milk consumption (<0.47 L daily). We excluded subjects with granulomatous conditions, liver disease, kidney disease, or diabetes and subjects taking anticonvulsants, barbiturates, or steroids.


RESULTS
Serum calcidiol rose promptly after cholecalciferol dosing from a mean (+/-SD) baseline of 27.1 +/- 7.7 ng/mL to a concentration maximum of 42.0 +/- 9.1 ng/mL. Seven percent of the supplemented cohort failed to achieve 32.1 ng/mL at any time point. The highest achieved concentration in any subject was 64.2 ng/mL. The control group had a nonsignificant change from baseline of -0.72 +/- 0.80 ng/mL during 4 mo.


CONCLUSIONS
Cholecalciferol (100,000 IU) is a safe, effective, and simple way to increase calcidiol concentrations. The dosing interval should be < or =2 mo to ensure continuous serum calcidiol concentrations above baseline. This trial was registered at www.clinicaltrials.gov as #NCT00473239.
Ilahi
Marium
M
Creighton University Medical Center, Omaha, NE 68131, USA.
Armas
Laura A G
LA
Heaney
Robert P
RP
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D019540:Area Under Curve; D050071:Bone Density Conservation Agents / Q000493:pharmacokinetics*; D002762:Cholecalciferol / Q000493:pharmacokinetics*; D015331:Cohort Studies; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008892:Milk; D010349:Patient Compliance; D011863:Radioimmunoassay; D012621:Seasons; D012880:Skin Pigmentation; D013472:Sunlight; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000097:blood; D014808:Vitamin D Deficiency / Q000188:drug therapy*; D044465:White People
D050071:Bone Density Conservation Agents; D014807:Vitamin D; D002762:Cholecalciferol; C104450:25-hydroxyvitamin D