Table 1.

The effect of ciprofloxacin on reversal of ABCB1-mediated MDR.

Compounds	SW620		SW620/AD300
	IC50 ± SD a (μM)	FR b	IC50 ± SD a (μM)	FR b
Paclitaxel	0.08 ± 0.01	[1.0]	27.38 ± 2.51	[342.2]
+ Ciprofloxacin 1 μM	0.09 ± 0.02	[1.1]	19.58 ± 1.86	[244.7]
+ Ciprofloxacin 5 μM	0.08 ± 0.01	[1.0]	5.71 ± 0.48	[71.3] c
+ Ciprofloxacin 10 μM	0.07 ± 0.01	[0.8]	0.81 ± 0.03	[10.1] c
+ Verapamil 10 μM	0.06 ± 0.01	[0.7]	0.92 ± 0.04	[11.5] c
Vincristine	0.07 ± 0.02	[1.0]	16.44 ± 1.22	[234.8]
+ Ciprofloxacin 1 μM	0.07 ± 0.01	[1.0]	10.21 ± 0.99	[145.8]
+ Ciprofloxacin 5 μM	0.06 ± 0.01	[0.8]	3.89 ± 0.24	[55.5] c
+ Ciprofloxacin 10 μM	0.05 ± 0.01	[0.7]	0.63 ± 0.03	[9.0] c
+ Verapamil 10 μM	0.06 ± 0.02	[0.8]	0.69 ± 0.04	[9.8] c
Cisplatin	2.23 ± 0.08	[1.0]	2.49 ± 0.09	[1.1]
+ Ciprofloxacin 1 μM	2.04 ± 0.09	[0.9]	2.51 ± 0.12	[1.1]
+ Ciprofloxacin 5 μM	2.17 ± 0.13	[0.9]	2.39 ± 0.19	[1.0]
+ Ciprofloxacin 10 μM	2.54 ± 0.09	[1.1]	2.78 ± 0.15	[1.2]
+ Verapamil 10 μM	2.69 ± 0.11	[1.2]	2.84 ± 0.14	[1.2]

^a IC₅₀ values are represented as mean ±SD of at least three independent experiments performed in triplicate.^b FR: Resistance fold was calculated by dividing the IC50 values of substrates in the presence or absence of inhibitor by the IC50 of parental cells without inhibitor. ^c p < 0.05 versus the control group without reversal agent.