Determination of Finasteride in Human Plasma by LC/MS/MS and Study on Its Pharmacokinetics

The study developed an LC/MS/MS method to determine finasteride levels in human plasma and examined its pharmacokinetics in 18 healthy male Chinese volunteers. The method demonstrated a linear calibration curve for finasteride concentrations ranging from 0.2 to 50.0 μg/L, with a lower limit of quantitation at 0.2 μg/L. It showed high precision and accuracy, with inter- and intra-day precision (RSD) below 10% and relative error within 3%. Key pharmacokinetic parameters included a half-life (t1/2ke) of 5.57 ± 1.60 hours, a maximum concentration (Cmax) of 40.31 ± 10.89 μg/L, and a time to reach maximum concentration (tmax) of 2.31 ± 0.82 hours. The method was deemed suitable for clinical investigations due to its convenience, sensitivity, and specificity.