Pharmacokinetic Profile of Plasma Tocopherol Following Intramuscular Administration of Acetylated α-Tocopherol to Sheep

Abstract

Five sheep, with a mean BW of 45 kg, were given a single i.m. injection (600 IU) of dl-α-tocopherol acetate. Plasma concentration of α-tocopherol was best fitted to a single-compartment model. Two successive absorption processes were selected. The individual pharmacokinetic parameters were absorption rate constant, Ka1 = 0.29 ± 0.02/h; the second absorption rate constant, Ka2 = 0.03 ± 0.002/h; elimination half-life = 42.40 ± 1.70/h; mean residence time = 46 ± 0.92 h; and area under the curve = 290 ± 10.77 μg/h per ml. During the first absorption process, elimination half-life was 2.46 ± 0.22 h, and the second elimination half-life was 21.20 ± 1.72 h. The peak concentration of vitamin E plasma (4.78 ± 0.23 μg/ml) was observed at 14.6 ± 4.08 h after i.m. injection. The increase in vitamin E concentration occurred because of gradual hepatic hydrolysis of the absorbed acetylated tocopherol.