they would not inhibit each other’s metabolism

CYP Isozyme	IC₅₀ for Desvenlafaxine	IC₅₀ for CYP-Specific Inhibitor
CYP1A2	> 100 µM	0.02 µM α-Naphthoflavone
CYP2C8	> 100 µM	10 µM Quercitin
CYP2C9	> 100 µM	1 µM Sulfaphenazole
CYP2C19	> 100 µM	20 µM Tranylcypromine
CYP2D6: Bufuralol cocktail^a	50 µM	0.2 µM Quinidine
CYP2D6: Bufuralol^b	70 µM	ND
CYP2D6: Bufuralol plus desvenlafaxine^b	50 µM	ND
CYP2D6: Dextromethorphan^b	80 µM	ND
CYP2D6: Dextromethorphan plus desvenlafaxine^b	90 µM	ND
CYP3A4	> 100 µM	0.08 µM Ketoconazole

^aProbe utilized as component of a cocktail.
^bIn a separate set of experiments, bufuralol and dextromethorphan (5 µM) were analyzed separately with the internal standard 4'-hydroxydiclofenac (0.53 µM). These substrates were incubated separately so they would not inhibit each other’s metabolism, did not include control incubations containing a known CYP2D6 inhibitor, and the incubations were performed twice; desvenlafaxine 30 µM was added to the second set of incubations.
Abbreviations: CYP, cytochrome P450; IC₅₀, half-maximal inhibitory concentration; ND, not determined.

Table 3: Approximate IC₅₀ Values for Desvenlafaxine and Known Inhibitors of Specific CYP Enzymes.

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