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. Author manuscript; available in PMC: 2012 Oct 28.
Published in final edited form as: Free Radic Biol Med. 2011 Mar 12;50(11):1610–1619. doi: 10.1016/j.freeradbiomed.2011.03.007

Table 1.

Combination index values for gemcitabine-ascorbate regimens in pancreatic carcinoma cells.

Cell Gem:Asc ratio Combination index (IC50) Combination index (IC75) Combination index (IC90)
PAN-02 1:1 × 104 0.18 0.20 0.29
PAN-02 1:2 × 104 0.25 0.41 0.78
AsPC-1 1:1 × 104 1.20 0.98 0.89
AsPC-1 1:2 × 104 1.10 1.01 0.97
BxPC-3 1:1 × 104 1.01 0.87 0.92
BxPC-3 1:2 × 104 0.94 0.72 0.63
PANC-1 1:1 × 103 1.12 0.90 0.87
PANC-1 1:5 × 103 1.06 1.19 1.45
MIA PaCa-2 1:1 × 103 0.85 0.85 0.80
MIA PaCa-2 1:5 × 103 0.91 0.91 0.89
SU.86.86 1:1 × 103 0.72 0.71 0.83
SU.86.86 1:5 × 103 0.72 0.69 0.67
HPAF-II 1:5 0.83 0.35 1.00
HPAF-II 1:10 0.70 0.35 0.67
Hs 766T 1:5 0.85 0.83 0.99
Hs 766T 1:10 0.49 0.72 1.19

Combination index is a quantitative measure of the degree of gemcitabine:ascorbate interaction in terms of synergism (CI< 1), additive effect (CI = 1), or antagonism (CI> 1) for a given measurement of cytotoxicity (IC50, IC75, IC90 shown). Cytotoxicity was determined in at least three individual experiments per cell type by triplicate MTT assay determinations at 72 h postexposure.