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Updated: Aug 17, 2026

Dynamic Multiparameter Platelet Function Assessment Using a Capacitive Biosensor
Published on: May 2, 2025
Kinetic study of CYP3A4 activity on verapamil by capillary electrophoresis
Jie Zhang1, Pham Thi Thanh Ha, Yijia Lou
1Laboratory of Pharmaceutical Chemistry and Drug Analysis, Faculty of Pharmaceutical Sciences, K.U. Leuven, Van Evenstraat 4, B-3000 Leuven, Belgium.
Abstract:
The use of capillary electrophoresis (CE) for the determination of CYP3A4 activity with verapamil as a substrate was investigated. CYP3A4 activity was determined by the quantitation of the product, norverapamil, based on separation by CE. The separation conditions were as follows: capillary, 80.5 cm (75 microm i.d., 72 cm effective length); 50 mM sodium phosphate buffer (pH 8.8); 20 kV (100 microA) applied voltage; UV detection at 200 nm; capillary temperature, 25 degrees C. With the developed CYP3A4 activity assay and the Lineweaver-Burk equation, the Michaelis-Menten parameters Km and Vmax for formation of norverapamil from verapamil in the presence of CYP3A4 were determined and were 22.8+/-2.5 microM and 7.67+/-0.26 pmol/min/pmol (or 983 pmol/min/mg) CYP3A4, respectively.
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