Bliss Independence Model

Bliss independence model is based on the probability theory for independent events. The Bliss model was used to compute the expected combined effects of two drugs as the product of their individual effects on the basis of the assumption that there was no drug-drug interaction effect. The expected combination effect was calculated using Effect_(a+b) = E_(a) + E_(b) − E_(a) E_(b). The drug combinations were synergistic if their observed effects were higher than the expected combined effects, antagonistic if they were lower, and additive if they were equal. With the excess over Bliss (EOB) score, the drug combination effect is determined at each combination dose.