TABLE 2

Dose-effect relationships of the combination of AmB and allicin on Leishmania infantum promastigotesa

D1-D2 combination ratio% growth inhibition (EDn)CIDRIDose required (μM)
AmBAllicinAmBAllicin
0.01:5500.79 (moderate synergism)3.891.890.02311.69
750.65 (synergism)5.482.130.03517.69
900.54 (synergism)7.732.390.05326.75
950.49 (synergism)11.522.740.07135.45
0.01:10501.23 (moderate antagonism)4.141.010.02221.94
751.16 (slight antagonism)5.311.030.03736.49
901.09 (nearly additive)6.811.050.06160.71
951.05 (nearly additive)8.061.070.08585.82
0.01:20501.33 (moderate antagonism)6.920.840.01531.22
751.19 (slight antagonism)9.470.910.02347.48
901.07 (nearly additive)12.961.010.03672.23
950.99 (nearly additive)16.051.060.04896.07
  • a Drugs were combined at constant ratios (0.01:5, 0.01:10, and 0.01:20), and their dose-effect relationships were assessed by the Chou-Talalay method (17) using CalcuSyn software. CI was calculated by the combination index equation. CI of <1, 1, and >1 indicate synergism, additive effect, and antagonism, respectively, at different effective doses (ED50, ED75, ED90, and ED95). Synergistic effects (CI < 1) are in bold. DRI indicates the fold dose reduction allowed in a drug combination to reach a given degree of inhibition compared to the drug as a single agent. Computer-simulated dose-required values of each drug in combination to reach a given effect level are included.