In patients with advanced HIV infection, the virological response to salvage therapy containing nelfinavir is best predicted by the number of baseline RT inhibitor plus protease inhibitor-resistance mutations.

The response to ritonavir plus saquinavir in advanced HIV infection is unpredictable. A minority of patients respond with disappearance of HIV viraemia. In other patients, rapid cumulative emergence of protease mutations conferring resistance to treatment cannot always be prevented by good compliance and relatively high plasma drug levels.