New method for determination of dydrogesterone in human plasma for therapeutic drug monitoring in gynecological disorders.

A new simple, sensitive and selective liquid chromatography coupled with mass spectrometry (LC/MS) method for quantification of dydrogesterone in human plasma was validated.The analytes was eluted in 1.3 minutes on a reversed phase column (Zorbax SB-C18, 100 mm x 3.0 mm I.D., 3.5 microm) under isocratic conditions using a mobile phase of a 20 : 80 (v/v) mixture of ammonium acetate 1 mM and acetonitrile. The flow rate was 1 mL/min at the column temperature of 35 degrees C. The detection of the analyte was in MS/ MS mode using an atmospheric pressure chemical ionization source (APCI+, m/z 313 > m/z 295). The sample preparation was very simple and rapid and consisted in plasma protein precipitation from 0.2 mL plasma using 0.6 mL methanol.Calibration curves were generated over the range of 5-150 ng/mL with values for coefficient of determination greater than 0.997 and by using a weighted (1/y) linear regression. The values of precision and accuracy were less than 12.5% and 7.5%, respectively, both for within- and between-run analysis. The mean recovery of the analyte was 99.8%. This is the first reported method for analysis dydrogesterone in human plasma that uses protein precipitation as sample processing procedure. The validated LC/MS method could be applied for determination of dydrogesterone in human plasma for therapeutic drug monitoring in gynecological disorders.