Abstract

Objective: To evaluate the pharmacokinetic parameters and bioequivalence of two sildenafil tablets (20 mg) in healthy Chinese subjects.
Materials and methods: A random, crossover, self-control design was used. 20 healthy subjects including males and females were randomized into two groups. A single oral dose of the trial or reference preparation was given to the two groups of subjects after an overnight fast of 10 hours. Blood samples were taken at scheduled time points. Plasma concentrations of sildenafil and N-desmethyl sildenafil were measured by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). ANOVA was used to check the difference of the mean values of the pharmacokinetic parameters between the two preparations. Bioequivalence was determined by two one-sided t-tests and 90% confidence intervals.
Results: The quantitative range of sildenafil and N-desmethyl sildenafil was 2.000 – 200.0 ng/mL and 0.800 – 80.00 ng/mL, respectively. Plasma samples were stable, and there was no mutual interference between the analyte and internal standard. With the 90% confidence limit, the trial preparations AUC_0→t and C_max fall within 80.00 – 125.00% of the reference preparation’s AUC_0→t and C_max. The t_max of sildenafil and N-desmethyl sildenafil was ~ 0.9 hours and 1 hour, and the T_1/2 was 2.4 hours and 3.7 hours, respectively. The relative bioavailability of sildenafil and N-desmethyl sildenafil was 99.28 ± 3.30% and 99.20 ± 3.39%. No significant difference was found in every factor between the trial preparation and the reference preparation.
Conclusion: The UPLC-MS/MS method was successfully established to evaluate the pharmacokinetic parameters of sildenafil in healthy Chinese subjects. The trial preparation was bioequivalent to the reference preparation.

Author Details

Authors

• Jie Huang^{1, 2}
• Hualin Cai^{1, 2}
• Wenqun Li^{1, 2}
• Xiaomei Huang³
• Huiyu Guan³
• Xi Wang³
• Yamin Yin³
• Binbin He³
• Jian Huang³
• Bikui Zhang^{1, 2}

Departments

• ¹ Department of Pharmacy, The Second Xiangya Hospital,
• ² Institute of Clinical Pharmacy, Central South University, and
• ³ Xiangya Boai Rehabilitation Hospital, Changsha, China

Address


Prof. Bikui Zhang
Department of Pharmacy
The Second Xiangya Hospital
Central South University, Changsha 410000, China
Email: [email protected]

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