title: Kinetic behavior of three preparations of alpha-tocopherol after oral administration to postpubertal heifers.
abstract: OBJECTIVE
  To assess the kinetic behavior of 3 preparations of alpha-tocopherol (vitamin E) after oral administration to heifers.
  
  
  METHODS
  8 postpubertal Friesian heifers.
  
  
  METHODS
  A single oral bolus of 5,000 U of alpha-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 alpha-tocopherol were 4.86 +/- 0.49 microg/ml, 5.03 +/- 0.39 microg/ml, and 5.08 +/- 0.56 microg/ml after administration of oil, liposomal, and cyclodextrin preparations, respectively. Plasma concentrations peaked 21 to 34 hours after administration. The disappearance rate constant (Kd) was less after administration of alpha-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 alpha-tocopherol, compared with alpha-tocopherol in oil, but these differences were not significant.
  
  
  CONCLUSIONS
  The lower Kd determined for alpha-tocopherol encapsulated in liposomes suggests that this formulation may result in longer persistance of the vitamin in plasma than the other 2 preparations. Dietary supplementation with alpha-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.
authors.affiliation: Department of Scienze Animali, Vegetali e dell'Ambiente, University of Molise, Campobasso, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Bontempo
authors.forename: A
authors.initials: A
authors.lastname: Baldi
authors.forename: F
authors.initials: F
authors.lastname: Cheli
authors.forename: F
authors.initials: F
authors.lastname: Fantuz
authors.forename: I
authors.initials: I
authors.lastname: Politis
authors.forename: S
authors.initials: S
authors.lastname: Carli
authors.forename: V
authors.initials: V
authors.lastname: Dell'Orto
mesh_terms: D000284:Administration, Oral; D000821:Animal Feed; D000818:Animals; D019540:Area Under Curve; D002417:Cattle / Q000378:metabolism* / Q000502:physiology; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D003505:Cyclodextrins / Q000008:administration & dosage; D005260:Female; D006207:Half-Life; D016018:Least-Squares Analysis; D008081:Liposomes / Q000008:administration & dosage; D014810:Vitamin E / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*
chemical_list: D003505:Cyclodextrins; D008081:Liposomes; D014810:Vitamin E