title: High-performance liquid chromatographic determination of doxazosin in human plasma for bioequivalence study of controlled release doxazosin tablets.
abstract: A highly sensitive high-performance liquid chromatographic quantification method with fluorescence detection was developed and validated for the determination of doxazosin in human plasma. The developed method employed one-step extraction of doxazosin from plasma matrix with ethyl acetate using propranolol as an internal standard. Chromatographic separation was obtained within 8.0 min using a reverse-phase Capcell-Pak C(18) column (150 x 4.6 mm i.d., 5 microm) and the mobile phase consisted of methanol-water containing 10 mM perchloric acid and 1.8 mM sodium heptane sulfonic acid (50:50, v/v) and was set at a flow rate of 1.5 mL/min. The calibration curve constructed was linear in the range of 0.3-50.0 ng/mL. The proposed method achieved a lower limit of quantification of 0.3 ng/mL, better than the reported HPLC methods. Average recoveries of doxazosin and the internal standard from human plasma matrix were 87.0 and 85.9%, respectively. The present method was validated by evaluating the precision and accuracy for inter- and intraday variation in the concentration range 0.3-50 ng/mL. The precision values expressed as relative standard deviations in the inter- and intraday validation were 1.17-6.29 and 0.84-5.94%, respectively. This method was successfully applied to the bioequivalence study of two doxazosin controlled release tablets in healthy, male human subjects.
authors.affiliation: Division of Pharmaceutical Sciences, College of Pharmacy, Chung-Ang University, 221 Heuksuk-dong, Dongjak-gu, Seoul 156-756, South Korea.
authors.forename: Young Jae
authors.initials: YJ
authors.lastname: Kim
authors.forename: Yoonjin
authors.initials: Y
authors.lastname: Lee
authors.forename: Myung Joo
authors.initials: MJ
authors.lastname: Kang
authors.forename: Jin Seo
authors.initials: JS
authors.lastname: Huh
authors.forename: Mikyeong
authors.initials: M
authors.lastname: Yoon
authors.forename: Jaehwi
authors.initials: J
authors.lastname: Lee
authors.forename: Young Wook
authors.initials: YW
authors.lastname: Choi
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003692:Delayed-Action Preparations / Q000032:analysis; D017292:Doxazosin / Q000097:blood*; D004355:Drug Stability; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013810:Therapeutic Equivalency
chemical_list: D003692:Delayed-Action Preparations; D017292:Doxazosin