Table 1.

Synergy and antagonism scale in drug combination studies ²¹.

Synergism		Antagonism
CI Value	Effect Description	CI Value	Effect Description
<0.1	Very strong synergism	1.10-1.20	Slight antagonism
0.1-0.3	Strong synergism	1.20-1.45	Moderate antagonism
0.3-0.7	Synergism	1.45-3.3	Antagonism
0.7-0.85	Moderate synergism	3.3-10	Strong antagonism
0.85-0.9	Slight synergism	>10	Very strong antagonism

CI values <1, =1, >1 indicate synergism, additive effect and antagonism.