Raltegravir (Isentress)is an first-in-class, orally-available, oxadiazole-based inhibitor of HIV-1 integrase, inhibiting strand transfer in vitro with an IC50 of 2-7 nM. [1] It is >1000-fold more selective for HIV-1 integrase when compared to other phosphoryltransferases, such as the polymerase and RNase H activities of HIV-1 reverse transcriptase and the human polymerases alpha, beta, and gamma.

Raltegravir has a IC95 in human T lymphoid cell cultures of 31 nM and was also active against HIV-2 when tested in CEMx174 cells, with an IC95 of 6nM. [2]

Raltegravir has been shown to be a potent and selective against Xenotropic murine leukemia-related retrovirus (XMRV) at submicromolar concentrations in MCF-7 breast cancer (EC50 = 5 nM, EC90 = 3.5 uM) and LNCaP prostate cancer (EC50 = 30 nM, EC90 0.46 um) cell lines. [3]