Table 3. Summary of the IC₅₀ (nM) values obtained for the antagonist drugs in combinations as indicated, along with their ‘predicted’ ACB scores.

Drug	IC50 ± SEM (nM)	‘Predicted’ ACB score
Dicycloverine/Cyclobenzaprine	10 ± 1.3 a *	5
Dicycloverine/Amitriptyline	22 ± 2.7 b *	6
Amitriptyline/Cyclobenzaprine	65 ± 9.4	5
Dicycloverine/Cimetidine	66 ± 3.4 c ***	4
Cyclobenzaprine/Cimetidine	560 ± 30 d *	3
Amitriptyline/Cimetidine	670 ± 45	4

Values represent the mean IC₅₀ values (n = 3), ± SEM (nM) for each combination of two drugs.

Compared IC₅₀s;

a dicycloverine/cyclobenzaprine vs dicycloverine/amitriptyline,

b dicycloverine/amitriptyline vs amitriptyline/cyclobenzaprine,

c dicycloverine/cimetidine vs cyclobenzaprine/cimetidine and

d cyclobenzaprine/cimetidine vs amitriptyline/cimetidine.

* P < 0.05,

** P < 0.01,

*** P < 0.001

‘Predicted’ ACB score from linear addition of individual drug ACB scores (Table 2).