Evaluation of the oral vitamin E absorption test in horses.
An oral vitamin E absorption test used in human beings was modified for use in horses. The most appropriate techniques with which to measure gastrointestinal tract absorption of vitamin E (alpha-tocopherol) in horses were developed. Vitamin E was administered orally, and serum values of alpha-tocopherol were measured by use of high-performance liquid chromatography at 0, 3, 6, 9, 12, and 24 hours after vitamin E administration. Variables included comparison of 2 dosages (45 and 90 IU/kg of body weight), routes of administration, and absorption dynamics of 3 preparations of dl-alpha-tocopherol. Absorption of the 2 doses of dl-alpha-tocopherol acetate indicated a dose response; the area under the curve at 24 hours (AUC24) was 4.3 micrograms.h/ml for the 45-IU/kg dose and 32.2 micrograms.h/ml (P less than 0.01) for the 90-IU/kg dose. Maximal absorption was apparent when vitamin E was naturally consumed in grain, compared with administration of identical preparations by stomach tube or paste. In the same horses, dl-alpha-tocopherol and dl-alpha-tocopherol acetate plus polyethylene glycol had statistically similar absorption curves and both had significantly greater AUC24, compared with dl-alpha-tocopherol acetate; values for the 3 compounds were 23.6, 25.8, and 12.6 micrograms.h/ml, respectively. The AUC24 varied between individual horses, but time of peak value was consistently observed between 6 and 9 hours.(ABSTRACT TRUNCATED AT 250 WORDS)
Craig
A M
AM
College of Veterinary Medicine, Oregon State University, Corvallis 97331.
Blythe
L L
LL
Rowe
K E
KE
Lassen
E D
ED
Walker
L L
LL
D000284:Administration, Oral; D000818:Animals; D005069:Evaluation Studies as Topic; D005260:Female; D006736:Horses / Q000378:metabolism*; D007408:Intestinal Absorption; D008297:Male; D012016:Reference Values; D015203:Reproducibility of Results; D014810:Vitamin E / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*
D014810:Vitamin E