Annotation of U.S. Food and Drug Administration (FDA) label information
for darifenacin
and CYP2D6
Summary
The FDA-approved drug label for darifenacin (Enablex) notes that CYP2D6 poor metabolizers may have increased maximum plasma concentrations of darifenacin, as compared to CYP2D6 extensive metabolizers. However, the label does not comment on the clinical significance of these increased concentrations.
Annotation
Darifenacin (Enablex) is a muscarinic antagonist indicated for treatment of overactive bladder. The FDA-approved drug label for darifenacin notes that its metabolism is primarily mediated by CYP2D6 and CYP3A4.
Excerpt from the darifenacin (Enablex) drug label:
A subset of individuals (approximately 7% Caucasians and 2% African Americans) are poor metabolizers (PMs) of CYP2D6 metabolized drugs. Individuals with normal CYP2D6 activity are referred to as extensive metabolizers (EMs). The metabolism of darifenacin in PMs will be principally mediated via CYP3A4. The darifenacin rations (PM versus EM) for Cmax and AUC following darifenacin 15 mg once daily at steady-state were 1.9 and 1.7, respectively.
For the complete drug label text with sections containing pharmacogenetic information highlighted, see the darifenacin drug label.
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