(02-06-11) Pharmacokinetics of a single, large dose of cholecalciferol1?3

Marium Ilahi, Laura AG Armas, and Robert P Heaney
ABSTRACT
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.
Design: 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).Weexcluded 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 _2 mo to ensure continuous serum calcidiol concentrations
above baseline. This trial was registered at www.clinicaltrials.
gov as #NCT00473239.

Source: Am J Clin Nutr 2008;87:688 ?91.

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