TABLE 2

Correlation of formation rates of 8-hydroxyefavirenz and 7-hydroxyefavirenz from efavirenz (10 μM) with the activities of different P450 enzymes in HLM samples (n = 15)

Efavirenz (10 μM) was incubated with microsomes from different human livers (0.25 mg/ml) and an NADPH-generating system for 15 min at 37°C. Data were analyzed using the nonparametric correlation test (Spearman r). The activity of each isoform was determined using the respective specific substrate probe reaction (see Materials and Methods). CYP3A was assayed using testosterone (T).

P450 Isoforms	Efavirenz Metabolites
	7-OHEFV		8-OHEFV
	Spearman r	p Value^†	Spearman r	p Value^†
CYP1A2	0.31	0.26	0.53	0.044
CYP2A6	0.80	0.0003	0.62	0.014
CYP2B6	0.57	0.03	0.81	0.0003
CYP2C8	0.58	0.02	0.58	0.03
CYP2C9	0.30	0.27	0.37	0.17
CYP2C19	0.28	0.32	0.03	0.93
CYP2D6	−0.20	0.48	0.08	0.79
CYP2E1	0.01	0.98	0.22	0.43
CYP3A (T)	0.61	0.015	0.37	0.18
CYP4A11	0.25	0.36	0.004	0.99
FMO	0.21	0.45	0.06	0.84

↵† p < 0.05 is considered statistically significant.