Table 1

Inhibition of diclofenac metabolism in incubations with monkey liver microsomes

Inhibitor or AntibodyQuinidineDiclofenac% Control1-a
μM
Troleandomycin (40 μM)05025
Ketoconazole (2 μM)05030
L-754,394 (10 μM)05030
Anti-3A IgG (monoclonal) (5 mg/nmol CYP)05011
Anti-3A IgG (peptide) (5 mg/nmol CYP)05030
Anti-3A IgG (monoclonal) (5 mg/nmol CYP)100503 (10)1-b
Anti-3A IgG (peptide) (5 mg/nmol CYP)1005031

Diclofenac and GSH in phosphate buffer were added to monkey liver microsomes suspended in phosphate buffer (0.1 M, pH 7.4) containing EDTA. Microsomes were preincubated with ketoconazole for 10 min and with troleandomycin or L-754,394 in the presence of NADPH for 15 min at 37°C. Microsomes were preincubated with anti-CYP IgG for 30 min at room temperature. Reactions were initiated by adding NADPH and continued for an additional 10 min. The products were analyzed by LC/MS/MS. All in vitro experiments were performed in duplicate.

  • 1-a % control was based on the formation of 5-OH-4-GS-diclofenac and 5-OH-6-GS-diclofenac in test incubations relative to the values in control experiments that lacked inhibitors.

  • 1-b Number in parentheses represents percentage of metabolites formed in incubations containing the monoclonal antibody and quinidine in comparison to controls containing preimmune IgG but no quinidine.