Comparison of plasma alpha- and gamma-tocopherols after oral and intramuscular administration of RRR-alpha-tocopherol or RRR-gamma-tocopherol to weanling pigs.

Equimolar amounts of either RRR-alpha-tocopherol (alpha-TOH) or RRR-gamma-tocopherol (gamma-TOH) were given as single doses orally and, as water-based emulsions, by intramuscular (i.m.) injection to weanling pigs. Venous blood was sampled at regular intervals and plasma was analyzed for comparison of alpha-TOH and gamma-TOH kinetics. Irrespective of the method of application no significant differences were found between alpha-TOH and gamma-TOH in (a) the maximum increase above initial concentration (delta C), (b) the time of peak concentration (tmax), and (c) the time from half-maximum concentrations on the ascending and the descending parts of the plasma curve. However, alpha-TOH was retained longer in plasma than gamma-TOH, and the areas-under-curve from Oh to 24 h and from Oh to 48 h (AUC0-24 and AUC0-48) were significantly greater for alpha-TOH. In diarrheic pigs given oral gamma-TOH, tmax was prolonged, delta C was lower and AUC0-24 and AUC0-48 were reduced compared with healthy pigs (p less than 0.05). The results indicate that pigs absorb both vitamers to a similar extent but that gamma-TOH is eliminated from plasma more rapidly.