Inhibitors of Uptake Transporters

Scientific Resources Inhibitors of Uptake Transporters

• Published on March 5, 2013
• Drug Transporters
• Scientific Posters

This poster was presented at the annual AAPS conference in 2013.

Full Title

Comparison of K_i and IC₅₀ Values for Prototypical Inhibitors of Uptake Transporters

Abstract

K_i values were determined for prototypical inhibitors of uptake transporters with an experimental design incorporating multiple substrate and inhibitor concentrations. The EMA’s Guideline on the Investigation of Drug Interactions (2012) recommends that K_i values be calculated for the inhibition of a transporter by investigational drugs and IC₅₀ values used only when a K_i value is not possible. Although K_i values have been reported for inhibitors of various uptake transporters, the methodology differs between labs and oftentimes relies on evaluation of a single concentration of the probe substrate combined with a mathematical extrapolation of the K_i value. The present study was designed to compare IC₅₀ values to K_i values experimentally determined with four concentrations of both probe substrate and inhibitor.

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