TABLE 11

Sample illustration of computer-simulated CI and DRI values for paclitaxel, cisplatin, and topotecan combinations at 50, 75, 90, and 95% inhibition of 833K teratocarcinoma cell growth (for experimental data, seeTable 10) Incubation was carried out for 96 h under conditions described in Chou et al. (1994). Data analysis was carried out for parameters (Dm and m) and statistics (r) by using CompuSyn.

Drug Combination Combination Ratio CI Valuesa at Inhibition of DRI Valuesb at inhibition of
50% 75% 90% 95% 50% 75% 90% 95%
Paclitaxel + cisplatin 1:100 0.887 0.781 0.690 0.636 1.89 2.27 2.72 3.07
2.79 2.94 3.11 3.22
Cisplatin + topotecan 10:1 0.557 0.562 0.570 0.577 3.04 3.23 3.43 3.58
4.39 3.97 3.59 3.36
Paclitaxel + topotecan 1:10 1.126 0.923 0.772 0.692 1.31 1.76 2.38 2.91
2.78 2.81 2.85 2.87
Paclitaxel + cisplatin + topotecan 1:100:10 1.150 0.738 0.480 0.361 1.87 3.25 5.65 8.23
2.76 4.22 6.46 8.63
3.98 5.19 6.77 8.11
  • a CI values are based on the combination index isobologram equations (eq. 16 for two drugs and eq. 20 for three drugs)

  • b DRI represents the order of magnitude (fold) of dose reduction that is allowed in combination for a given degree of effect compared with the dose of each drug alone (TC Chou, 1991; JH Chou, 1991). Upper values are for the first drug and lower values are for the second drug