A biaryl pyridylfuran P3 substituent on the hydroxyethylene isostere scaffold affords HIV protease inhibitors (PI's) with picomolar (IC50) potency against the protease enzymes from PI-resistant HIV-1 strains. Inclusion of a gem-dimethyl substituent afforded compound 3 with 100% oral bioavailability (dogs) and more than double the t1/2 of indinavir. Inhibition of multiple P450 isoforms is dependent on the regiochemistry of the pyridyl nitrogen in these ...