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. 2013 Apr 22;8(4):e61416. doi: 10.1371/journal.pone.0061416

Figure 6. TFV combined with NP-EFV or NP-SQV showed strong synergism.

Figure 6

Combination effects of free tenofovir (TFV) with efavirenz (EFV) or saquinavir (SQV) were quantified using the TZM-bl infectivity assay and the HIV-1 BaL isolate. The combination index (CI) was determined as described by Chou and Talalay. CI<1, = 1, and >1 indicate synergistic, additive, and antagonistic effects, respectively. The red line at CI = 1 represents the additive effect. (A) Combination of free TFV with free EFV or with nanoparticles loaded with EFV (NP-EFV) at a 1∶11 EFV∶TFV molar ratio demonstrated strong synergism, with the CI at 50% inhibition (CI50) of 0.01 and 0.07, respectively. (B) Combination of free TFV with free EFV or with NP-EFV at a 1∶600 NP-EFV∶TFV molar ratio demonstrated synergism and addition, with the CI50 of 0.58 and 1.05, respectively. (C) Combination of free TFV with free SQV at a 1∶5 TFV∶SQV molar ratio showed an additive effect (CI50 = 1.04) while free TFV combined with nanoparticles loaded with SQV (NP-SQV) at a 1∶3 TFV∶NP-SQV molar ratio showed a synergistic effect (CI50 = 0.07).