Early data from test-tube studies suggested that darunavir (Prezista) is active against HIV with high-level resistance to other protease inhibitors, and that resistance may develop more slowly than with other protease inhibitors^[1].

A sub-analysis of the POWER studies has shown that eleven protease mutations are associated with a reduced response to darunavir, some of which have not been seen with other protease inhibitors. The major mutation seen in these studies was V32I, while mutations I54L/M and I47V were also common. The researchers believe that a number of mutations need to accumulate before a reduced response to the drug is seen^[2].

There is little cross-resistance between darunavir and other protease inhibitors.