Figure 1.
Pharmacokinetics. (a–c) Serum concentrations of (a) all-trans retinoic acid (ATRA), (b) 13-cis retinoic acid (RA) and (c) 9-cis RA just before or 3 h after an oral dose 10 mg ATRA on day 1. Although pure ATRA was given, immediate isomerization occurs and the peak concentration of 13-cis RA exceeds that of ATRA. (d) Serum concentration of ATRA before and after 10 mg ATRA on the eighth day; there is no evidence of accumulation, but Cmax appears to be reduced compared with day 1, probably reflecting induction of degradative enzymes. (e,f) Serum concentrations of (e) ATRA and (F) 13-cis RA before and 3 h after a single dose of 60 mg retinyl palmitate, and then on day 8 at the same time as the baseline sample was taken for the volunteers shown in (d). Dotted lines show the polynomial smoothed curve, and the shaded band the 95% confidence limits.