Stereoselective analysis of flecainide enantiomers using reversed‐phase liquid chromatography for assessing CYP2D6 activity

Abstract

Stereoselective analyses of flecainide enantiomers were performed using reversed-phase high-performance liquid chromatography (HPLC) equipped with a polysaccharide-based chiral column (Chiralpak AS-RH) and fluorescence detector. Excitation and emission wavelengths were set at 300 and 370 nm, respectively. Flecainide enantiomers in serum and urine were extracted using diethyl ether. The mobile phase solution, comprising 0.1 m potassium hexafluorophosphate and acetonitrile (65:35, v/v), was pumped at a flow rate of 0.5 mL/min. The recoveries of flecainide enantiomers were greater than 94%, with the coefficients of variation (CVs) <6%. The calibration curves of flecainide enantiomers in serum and urine were linear in the concentration range 5-500 ng/mL and 0.75-15 µg/mL (r > 0.999), respectively. CVs in intra-day and inter-day assays were 1.8-5.8 and 3.4-7.5%, respectively. In a pharmacokinetic study, the ratios of (S)- to (R)-flecainide (S/R ratio) in the area under the curve and the amount of flecainide enantiomers excreted in urine were lower in a subject carrying CYP2D6*10/*10 than in subjects carrying CYP2D6*1/*2. The S/R ratio of trough serum flecainide concentration ranged from 0.79 to 1.16 in patients receiving oral flecainide. The present HPLC method can be used to assess hepatic flecainide metabolism in a pharmacokinetic study and therapeutic drug monitoring.

Advances and challenges in the pharmacokinetics and bioanalysis of chiral drugs

“…This type of binding results in up to twofold variations in free drugs in the plasma and the volume of distribution between the enantiomers. [29][30][31][32][33] For instance, many antiarrhythmic medicines that include disopyramide, encainide, flecainide, mexiletine, propafenone, and tocainide are marketed as racemates. The absorption of these chiral drugs was nonstereoselective.…”

“…In the distribution context, most of the chiral drugs exhibit stereoselectivity for plasma protein binding. This type of binding results in up to twofold variations in free drugs in the plasma and the volume of distribution between the enantiomers 29–33 . For instance, many antiarrhythmic medicines that include disopyramide, encainide, flecainide, mexiletine, propafenone, and tocainide are marketed as racemates.…”

Review of Chromatographic Methods Coupled with Modern Detection Techniques Applied in the Therapeutic Drugs Monitoring (TDM)

“…Rarely, the determination of enantiomers of chiral drugs in biological samples was described. Flecainide, a chiral compound administered as a racemic mixture for the treatment of supraventricular tachyarrhythmias in human serum and urine was analyzed by HPLC-FLD [ 102 ]. The detection of flecainide by FLD does not require a pre-column derivatization process.…”

Stability‐indicating chromatographic methods for determination of flecainide acetate in the presence of its degradation products; isolation and identification of two of its impurities

“…In the last decade, four liquid chromatographic methods (Kristoffersen et al, 2007;Lee et al, 2010;Sørensen, 2012;Doki et al, 2014), one capillary electrophoretic method (Pietraś et al, 2007) and one Thin Layer Chromatographic (TLC) method (Pietraś and Kowalczuk, 2010) have been reported. Only one spectrofluorimetric method (Chang et al, 1983) and one electrochemical method (Stefan et al, 1997) were reported.…”