Comparision of the phenol red, gravimetric, and synthesized mPEG-PR methods for correcting water flux using the single-pass intestinal perfusion method.

ABSTRACT

Phenol red and PEG-4000, the usual non-absorbable indicators, have non-negligible absorption problems in measuring water flux. mPEG-PR, combined phenol red with mPEG-4000, was first synthesized and could decrease absorption. However, its application has not been confirmed. The purpose of this study was to explore the applicability of mPEG-PR as a novel non-absorption indicator in the in situ single-pass intestinal perfusion (SPIP) experiment. Six model drugs (atenolol ranitidine, ibuprofen, ketoprofen, antipyrine, hydrochlorothiazide) were used to compare the accuracy of four measuring methods including phenol red, mPEG-PR, gravimetric, and non-corrected methods of correcting intestinal fluid transport. Moreover, we evaluated the correlations between the effective permeability coefficients (Peff) in rat and fraction dose absorbed (Fabs) in human, Peff in human, and apparent permeability coefficients (Papp) by the Ussing Chamber system using human tissue. Among these methods, mPEG-PR was the most reliable approach, which avoided the absorption of phenol red method and mucous shedding or water evaporation of gravimetric method. An excellent correlation was obtained between the Peff of rat and Fabs of human. Our results of this study indicated that mPEG-PR was a stable and accurate non-absorbable indicator to correct water flux in the in situ SPIP model, which could be developed to predict the human Fabs.