Synergism and Antagonism
Synergism and Antagonism
This Demonstration provides visualization of the synergism and antagonism phenomena encountered in the simultaneous application of two antimicrobial agents, drugs, or other biologically active compounds. In synergism, the combined effect is greater than that calculated from the sum of the individual effects, and in antagonism it is smaller. The merely additive effect, due to stoichiometry, is the straight black line connecting the activity of compound A alone with that of compound B alone on the plot of the combined activity versus the mixture's composition. Synergism manifests in a curve, or local part of a curve, lying above this line, and antagonism is below it. The curves generated are schematic and intended solely for illustration; there are four kinds: pure synergism, pure antagonism, synergism turning into antagonism, and antagonism turning into synergism.