Enantioselective assay of S(+)- and R(-)-propafenone in human urine by using RP-HPLC with pre-column chiral derivatization

Abstract

The enantioselective assay for S(+)-and R(-)-propafenone (PPF) in human urine that developed in this work involves extraction of propafenone from human urine and using S(+)-propafenone as internal standard, chiral derivatization with 2,3,4,6-tetra-O-β-D-glucopranosyl isothiocyanate, and quantitation by an RP-HPLC system with UV detection (γ-220 nm). A baseline separation of propafenone enantiomers was achieved on a 5-μm reverse phase ODS column, with a mixture of methanol:water:glacial acetic acid (25∶12∶0.02, v/v) as mobile phase. There was good linear relationship from 24.9 ng/ml to 1875.0 ng/ml for both of enantiomers. The regression equations of the standard curves based on C_S-PPF (or C_R-PPF) versus ratio of A_S-PPF/A_s (or A_R-PPF/A_s) werey=0.0032x−0.081, (r=0.999) for S-PPF andy=0.0033x+0.0039, (r=0.998) for R-PPF, respectively. The method’s limit of detection was 12.5 ng/ml for both enantiomers, and the method’s limit of quantitation was 28.2±0.52 ng/ml for S-PPF, 30.4±0.53 ng/ml for R-PPF (RSD<8%,n=5). The analytical method yielded average recovery of 98.9% and 100.4% for S-PPF and R-PPF, respectively. The relative standard derivation was no more than 6.11% and 6.22% for S-PPF and R-PPF, respectively. The method enabled study of metabolism of S(+)-and R(-)-propafenone in human urine. The results from 7 volunteers administered 150 mg racemic propafenone indicated that propafenone enantiomers undergo stereoselective metabolism and that in the human body, S(+)-propafenone is metabolized more extensively than R(-)-propafenone.