Kinetic behavior of three preparations of α-tocopherol after oral administration to postpubertal heifers

Objective - To assess the kinetic behavior of 3 preparations of α- tocopherol (vitamin E) after oral administration to heifers. Animals - 8 postpubertal Friesian heifers. Procedures - A single oral bolus of 5,000 U of α-tocopherol in oil or encapsulated in liposomes or cyclodextrin was administered to each cow, using a 4 x 4 design with 8 days between treatments. Blood samples for kinetic analyses were obtained at various times for 168 hours after treatment. Results - Mean (± SEM) maximal plasma concentrations of α-tocopherol were 4.86 ± 0.49 μg/ml, 5.03 ± 0.39 μg/ml, and 5.08 ± 0.56 μg/ml after administration of oil liposomal, and cyclodextrin preparations, respectively. Plasma concentrations peaked 21 to 34 hours after administration. The disappearance rate constant (K(d) was less after administration of α-tocopherol encapsulated in liposomes, compared with the other 2 preparations. Area under the concentration versus time curve was greater after administration of either encapsulated form of α- tocopherol, compared with α-tocopherol in oil, but these differences were not significant. Conclusions and Clinical Relevance - The lower K(d) determined for α-tocopherol encapsulated in liposomes suggests that this formulation may result in longer persistence of the vitamin in plasma than the other 2 preparations. Dietary supplementation with α-tocopherol encapsulated in liposomes may enhance plasma availability of this vitamin in cattle and could be useful during periods of increased vitamin E requirements, such as parturition and early stages of life.