Table 2.

Preliminary screening for potential mechanism-based inactivation of human liver microsomal CYP enzymes

	Inhibition difference (percentage of control)
	Phenacetin O-deethylation (CYP1A2)	Torsemide tolyl methylhydroxylation (CYP2C9)	(S)-Mephenytoin 4′-hydroxylation (CYP2C19)	Dextromethorphan O-demethylation (CYP2D6)	Testosterone 6β-hydroxylation (CYP3A)
Selegiline	0.5	N.O.	−10.7	6.0	0.5*
Clorgyline	21.6†	−14.3	−16.6	−4.8	0.8
Pargyline	−1.9	N.O.	N.O.	−8.8	1.3
Tranylcypromine	−7.4	−0.9	−12.1	−1.3	−6.7*
Phenelzine	25.4	46.8	24.2	11.9	12.5*
Isoniazid	11.4	14.8	18.0	4.0	15.9*
Iproniazid	−4.0	15.7	−0.7	4.0	−1.6
Moclobemide	3.1	N.O.	−3.0	9.9	−3.2

Monoamine oxidase inhibitors (20 µm) were co- and preincubated as described under Methods and the inhibition difference between co- and preincubation conditions determined. Data represent the mean of at least duplicate determinations.

^*Data from Polasek et al. (2004).

^†Results using 5 µm clorgyline. N.O., Co- and preincubation inhibition not observed.