Pharmacokinetic study of Ca-45 administered intravenously following intramuscular injection of vitamin D-3 or 25-hydroxyvitamin D-3 in early weaned lambs

The objective of this study was to evaluate the pharmacokinetic parameters of Ca-45 administered intravenously at a dose of 50 mu Ci in young lambs. T he experiment was performed on 18 female lambs allocated to three treatment s. Six animals received intravenous calcium only; six received intramuscula rly vitamin D-3 8 days prior to the administration of calcium; and six rece ived intramuscularly 25-hydroxyvitamin D-3 5 days prior to the administrati on of calcium. Blood samples were collected from 15 min up to 8 days after the administration of Ca-45. The different pharmacokinetic parameters (area under the curve, clearance, mean residence time and volume of distribution ) were estimated using non-compartmental and compartmental approaches. Stat istical analysis of the results showed no significant differences in the ph armacokinetic parameters of the three groups. It can be concluded that vita min D does not modify either the elimination or the distribution of calcium in the lambs receiving adequate dietary vitamin D. (C) 1999 Elsevier Scien ce Inc. All rights reserved.