Table I.

The classification of the combination index (CI) and anti-tumor activity. The CI value of between 0.9 and 1.1 represent additivity. The CI value less than 0.9 represents synergism while the value above 1.1 means antagonism.

Synergism		Antagonism
CI value	Synergy category	CI value	Antagonism category
0.85–0.9	Slight synergy	1.1–1.2	Slight antagonism
0.7–0.85	Moderate synergy	1.2–1.45	Moderate antagonism
0.3–0.7	Synergy	1.45–3.3	antagonism
0.1–0.3	Strong synergy	3.3–10	Strong antagonism
<0.1	Very strong synergy	>10	Very strong antagonism