Table 3.

Computer-simulated combination index of two- to three-drug combinations at 50%, 75%, 90% and 95% inhibition of HCV replicon replication

	CI values at inhibition of
Treatment	Ratio	50%	75%	90%	95%	CIwt
2′-C-MeC + IFN-α2b	1:3	0.2	0.3	0.3	0.3	0.3
2′-C-MeC + IFN-α2b	1:2	1.7	0.6	0.3	0.3	0.5
2′-C-MeC +IFN-α2b	1:1	0.8	0.5	0.3	0.3	0.4
2′-C-MeC + IFN-α2b	2:1	0.3	0.2	0.2	0.4	0.3
2′-C-MeC + IFN-α2b + RBV	2:1:1	1.4	0.9	0.9	1.4	1.1
2′-C-MeC + IFN-α2b + RBV	1:1:1	0.6	0.5	0.5	0.6	0.5
2′-F-C-MeC + IFN-α2b	1:10	1.7	0.9	0.6	0.5	0.7
2′-F-C-MeC + IFN-α2b	1:5	1.3	0.8	0.5	0.5	0.7
2′-F-C-MeC + IFN-α2b	1:1.5	0.3	0.3	0.3	0.4	0.3
2′-F-C-MeC + IFN-α2b	1:1	0.7	0.3	0.3	0.3	0.3
2′-F-C-MeC + IFN-α2b + RBV	2:1:1	2.3	1.0	0.8	1.0	1.1
2′-F-C-MeC + IFN-α2b + RBV	1:1:1	2.2	0.8	0.5	0.6	0.8
2′-F-C-MeC + IFN-α2b + RBV	1:1.5:1.5	1.1	0.9	0.9	1.1	1.0

Combination index (CI) values were determined for a mutually exclusive interaction using CalcuSyn program (Biosoft, Ferguson, MO, USA). CI <1, =1 or >1 indicates synergism, additive effect and antagonism, respectively. CI _wt weighted average CI value was assigned as = [CI₅₀ + 2CI₇₅ + 3CI₉₀, + 4CI₉₅]/10 (see review [21]). IFN, interferon; RBV, ribavirin.