The metabolic inhibition model which predicts the intestinal absorbability and Metabolizability of drug: Theory and experiment |
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Authors: | Takashi Mizuma Shoji Awazu |
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Institution: | (1) Department of Biopharmaceutics and Drug Rational Research Center, School of Pharmacy, Tokyo University of Pharmacy and Life Science, Japan |
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Abstract: | The intestinal absorption of analgesic peptides (leucine enkephalin and kyotorphin) and modified peptides in rat were studied.
Although these peptides were not absorbed, the absorbability (absorption clearance) of these peptides were increased in the
presence of peptidase inhibitors. In order to kinetically analyze these phenomena, we proposed the metabolic inhibition model,
which incorporated the metabolic clearance (metabolizability) with the absorption clearance. Metabolic activity was determined
with intestinal homogenates. The higher the metabolic clearance was, the lower was the absorption clearance. The relationships
between the absorption clearance and the metabolic clearance of the experimental data as well as of the theoretical values
were hyperbolic. This model predicted the maximum absorption clearances of cellobiose-coupled leucine enkephalin (0.654 μl/min/cm)
and kyotorphin (0.247 μl/min/cm). Details of the experimental methods are described. |
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