4.6. Chou–Talalay Combination Index

The combinatory effects of drugs were analyzed by the proliferation assay as described in the proliferation assay section, using an 8 × 8 matrix format to assess 8 different concentrations in three independent experiments. The average matrix was then, screened to 6 concentrations to ensure the removal of unreliable data with a r > 0.95, as previously described [16]. After analyzing the proliferation assay, the Chou–Talalay combination index (CI) method was calculated using CompuSyn software as described [16,43] to assess the synergetic effect. CI > 1 indicated antagonism, CI = 1 indicated an additive effect and CI < 1 indicated a synergetic effect.