Table 1.
In vitro anti-HBV activity and cytotoxicity of the three compounds used singly and in two-drug combinations in HepAD38 systema
| Compound | Ratio | EC50 (μM) | EC90 (μM) |
|---|---|---|---|
| TDF | NA | 0.01 (0.002–0.02) | 0.13 (0.03–0.25) |
| TFV | NA | 0.34 (0.11–0.93) | 3.72 (1.11–13.7) |
| (-)-FTC | NA | 0.05 (0.02–0.07) | 0.72 (0.18–1.42) |
| TDF + (−)-FTC | 1:1 | 0.01 (0.01–0.02) | 0.13 (0.01–0.18) |
| TDF + (−)-FTC | 1:2 | 0.01 (0.005–0.02) | 0.12 (0.07–0.22) |
| TDF + (−)-FTC | 1:5 | 0.02 (0.02–0.03) | 0.14 (0.13–0.15) |
| TDF + (−)-FTC | 1:10 | 0.02 (0.01–0.02) | 0.13 (0.11–0.15) |
| TFV + (−)-FTC | 1:1 | 0.02 (0.02–0.03) | 0.15 (0.12–0.18) |
| TFV + (−)-FTC | 2:1 | 0.33 (0.21–0.51) | 5.64 (2.04–15.6) |
| TFV + (−)-FTC | 5:1 | 1.00 (0.75–1.34) | 5.07 (3.47–7.40) |
a
All values represent the average of two experiments, and samples were performed in duplicate. EC50 and EC90, effective concentrations required to reduce HBV levels by 50% and 90%, respectively, on day 5. The values in parentheses indicate 95% confidence intervals generated by using the CalcuSyn program. The cytotoxic concentrations that inhibited cell growth by 50% (CC50s) in parent HepG2 cells were >10 μM for all compounds or compound combinations tested. Note that for the combination-drug studies, values were determined from standard curves for the first compound (either TDF or TFV). NA, not applicable.