Unexpected interaction between CYP3A4 and BI 11634: is BI 11634 interacting with CYP3A4 similar to nifedipine?

Background: Interactions between cytochrome P450 3A4 (CYP3A4) and its substrates are complex with multiple binding sites within the active site. BI 11634 is a factor Xa inhibitor in drug development and its interaction with CYP3A4 was evaluated.

Methods: Reaction phenotyping studies were conducted to determine human isoform(s) of cytochrome P450 responsible for BI 11634 metabolism using recombinant CYPs and specific chemical inhibitors.