Over the last decade, the development of in vitro MDR modulators has been remarkably successful, yet to date no agent has displayed significant clinical efficacy. 6 This is largely due either to the inherent toxicity of these compounds or to the heightened toxicity of the antineoplastic agents when co-administered with the modulator. ... In the preceding article, we described a novel class of 2,4,5-trisubstituted imidazoles (A) with potent Pgp inhibitory profile. 7 We ...