Abstract
In order to compare the bioavailabilities of various forms of commercial vitamin B_6 (B_6) preparation, the changes of blood total B_6, pyridoxal 5'-phosphate (PLP) level and urinary excretion of 4-pyridoxic acid (PIC) were studied after oral administration of ordinary dose for these preparations in ten healthy male adults. The T_<max.> of total B_6 and PLP level after administration of calcium pyridoxal 5'-phosphate (PLP-Ca) was the shortest one, and also the C_<max.> of those were the highest. But the ΔAUC (24 hours) for pyridoxine hydrochloride (PN-HCl) was the largest among these three preparations. The 3 hours urinary PIC excretion ratio for PLP-Ca was the highest, and no significant differences in 24 hours excretion ratio were found among them. The major component of serum B_6 at the point of C_<max.> for PLP-Ca was pyridoxal (PL). The blood total B_6 level at the point of C_<max.>, ΔAUC and also 3 hours PIC excretion ratio showed the largest CVs in the PLP enteric coating tablet (PLP_<ent.>) group. consequently it was considered that the absorption of PLP_<ent.> was poorest in reproducibility. The ascending tendencies of baseline levels of total B_6 in serum and erythrocyte were found to be prominent in PLP-Ca group.
