FIG. 5.
Representation of the change in bioavailability based on activity of the subject's transporters. The mathematical representation of this is as follows: F = 1 − E, where E is the extraction ratio. In this case, extraction would be due to transporters and nontransporters. E = (ENT + ET), where ENT is the extraction due to nontransporters and ET is the extraction due to the transporters; F = 1 − (ENT + ET), ENT = percent × E, and ET = (1 − percent) × E. Therefore, if the transporters are inhibited after day 1, bioavailability could be represented as follows: F (day 1) = 1 − (ENT + ET) or 1 − E, and F (day 21) = 1 − ENT or 1 − (percent × E).