Individualizing salvage regimens: the inhibitory quotient (Ctrough/IC50) as predictor of virological response.

Increased drug levels could overcome resistance and improve the response to a salvage regimen. We evaluate the inhibitory quotient (IQ, Ctrough/protein-binding corrected IC50) as a predictor of virological response in 52 patients included in two dual protease inhibitor (PI)-based salvage regimens. The HIV-RNA level decrease at 12 weeks was greater in patients who achieved an IQ greater than 1. The IQ could be useful to improve the virological response to a dual PI salvage regimen.