Pharmacokinetics and Amounts of 25-Hydroxycholecalciferol in Sheep Affected by Osteodystrophy

Open Access
Publisher Website
Google Scholar
Abstract
Amounts of 25-hydroxycholecalciferol in plasma were measured in 2 groups (A and B) of lambs (Experiment 1) and in 2 groups (C and D) of wethers (Experiment 2). Groups A (8 lambs) and C (9 wethers) consisted of animals born and raised in total confinement; these animals exhibited an osteodystrophic condition. Groups B (4 lambs) and D (10 wethers) consisted of healthy animals born and raised in a conventional barn with free access to an open barn yard (i.e., exposure to sunshine). The 25-hydroxycholecalciferol in plasma of both groups of sick animals, Group A (12.9 ng/ml) and Group C (18.0 ng/ml), were lower than the amounts of the 2 corresponding groups of healthy animals, Group B (29.2 ng/ml) and Group D (32.5 ng/ml). Pharmacokinetic analysis of 25-hydroxycholecalciferol in affected lambs following intramuscular injection of 1,000,000 IU [international unit] vitamin D3 indicated that transport of vitamin D3 from the site of injection to the liver and its metabolism to 25-hydroxycholecalciferol were rapid. Peak 25-hydroxycholecalciferol occurred at .6 wk, and half-life was 3.1 wk.