Table 4.

Efficiency indices used to guide drug development. LE = ligand efficiency, BEI = binding efficiency index, LLE = ligand lipophilicity efficiency, LELP = ligand-efficiency-dependent lipophilicity efficiency. Indices were calculated as described before [22,23]: LE = −1.4(logIC₅₀)/N_{heavy atoms}, BEI = −logIC₅₀/(molecular weight/1000), LLE = −logIC₅₀ − ${\mathsf{\mu }\mathrm{HPLC} \log P}_{\mathrm{OW}}^{\mathrm{pH} 7.4}$, LELP = ${\mathsf{\mu }\mathrm{HPLC} \log P}_{\mathrm{OW}}^{\mathrm{pH} 7.4}/\mathrm{LE}$.

Substance	LE (kcal/mol/Heavy Atom)	BEI	LLE	LELP
1	0.27	14.1	3.5	11.8
1a	0.20	10.7	0.3	24.0
1b	0.22	11.4	0.9	22.9
2	0.32	16.7	3.1	12.3
2a	0.28	14.7	2.2	14.8
2b	0.27	14.5	2.3	14.4
2c	0.25	13.1	1.6	17.1
2d	0.19	9.9	0.8	22.2