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. 2012 Jun 8;7(6):e38583. doi: 10.1371/journal.pone.0038583

Table 1. Combination index (CI) values for TC-1 cells treated with Radachlorin/PDT and As4O6.

Day 1 Day 2 Day 3 Day 4
As4O6 PDT f*(%) CI** f(%) CI f(%) CI f(%) CI
3uM 0.2ug/ml 17.3 1.61 9.7 1.16 8.2 0.98 8.7 0.67
3uM 0.15ug/ml 22.6 1.52 12.7 1.13 15.7 1.02 26.4 1.19

The combination index (CI) values were calculated using the Chou and Talalay mathematical model for drug interaction on Calcusyn software. A CI was equal to 1 denotes additivity; antagonism if the CI>1; CI values between 1 and 0.7 indicate slight synergism; 0.7 to 0.3, synergism; <0.3, strong synergism. *Viability.