A Determination of the Biological Half-life of 25-Hydroxyvitamin D3 in Beagles

Abstract

The biological half-life of 25-hydroxyvitamin D^ in four beagles was determined from serum samples using a precise and specific high-performance liquid chromatographic (HPLC) assay. Initial baseline levels ranging from l6.3 to 28.3 ng/ml of serum were established. Single rapid intravenous injections containing 20 p.g of 25-hydroxyvitamin Do were administered. Blood samples were then drawn at specified periods of time, and the serum v/as separated and assayed. The biological halflife based on a two compartment, single bolus injection model ranged from 28.5 to more than 400 days. The mean half-life for three of the dogs was 43.3 ± 15.0 days. The fourth dog appeared to be an unusual case.