Alfentanil N-deakylation: Monitoring the Formation of N-phenylpropionamide (AMX) to Determine CYP3A4 Activity in Vitro

Alfentanil is a synthetic analgesic cleared exclusively by hepatic metabolism. Due to the highly linear correlation between alfentanil systemic clearance and CYP3A4 activity, as well as the direct pharmacologic effects on pupil size, it has been used as a non-invasive metabolic probe for CYP3A4 activity in vivo. AMX is a direct metabolite of alfentanil, evaluated in this study for its potential to measure CYP3A4 activity in vitro.