RT Journal Article
SR Electronic
T1 Physiologically based pharmacokinetics of radioiodinated human beta-endorphin in rats. An application of the capillary membrane-limited model.
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 540
OP 550
VO 15
IS 4
A1 Sato, H
A1 Sugiyama, Y
A1 Sawada, Y
A1 Iga, T
A1 Hanano, M
YR 1987
UL http://dmd.aspetjournals.org/content/15/4/540.abstract
AB In order to simulate the distribution and elimination of radioiodinated human beta-endorphin (125I-beta-EP) after iv bolus injection in rats, we proposed a physiologically based pharmacokinetic model incorporating diffusional transport of 125I-beta-EP across the capillary membrane. This model assumes that the distribution of 125I-beta-EP is restricted only within the blood and the tissue interstitial fluid, and that a diffusional barrier across the capillary membrane exists in each tissue except the liver. The tissue-to-blood partition coefficients were estimated from the ratios of the concentration in tissues to that in arterial plasma at the terminal (pseudoequilibrium) phase. The total body plasma clearance (9.0 ml/min/kg) was appropriately assigned to the liver and kidney. The transcapillary diffusion clearances of 125I-beta-EP were also estimated and shown to correlate linearly with that of inulin in several tissues. Numerically solving the mass-balance differential equations as to plasma and each tissue simultaneously, simulated concentration curves of 125I-beta-EP corresponded well with the observed data. It was suggested by the simulation that the initial rapid disappearance of 125I-beta-EP from plasma after iv injection could be attributed in part to the transcapillary diffusion of the peptide.