OBJECTIVE  To evaluate the bioequivalence of the test and reference formulations of varenicline tartrate in healthy Chinese subjects under fasting and fed conditions.

METHODS  This study employed a single-center, randomized, open-label, single-dose, two-period, two-sequence crossover design. A total of 24 subjects were enrolled in each group(fasting and fed), and each subject received a 1 mg dose of either the test or reference formulation in each period. Varenicline plasma concentrations were measured using LC-MS/MS, and pharmacokinetic parameters were calculated using WinNonlin 8.1 software to assess bioequivalence.

RESULTS  In the fasting group, the pharmacokinetic parameters of the test and reference formulations were as follows: C_max (5.73±1.23) ng·mL⁻¹ vs (5.47±1.05) ng·mL⁻¹, AUC_0-t (107.57±17.70) h·ng·mL⁻¹ vs (111.78±25.29) h·ng·mL⁻¹, AUC_0-∞ (111.48±18.87) h·ng·mL⁻¹ vs (116.33±27.74) h·ng·mL⁻¹, T_max 1.50 h vs 1.50 h, t_1/2 (20.37±4.14) h vs (20.23±3.81) h. In the fed group, the pharmacokinetic parameters for the test and reference formulations were: C_max (5.88±1.02) ng·mL⁻¹ vs (6.26±1.13) ng·mL⁻¹, AUC_0-t (107.72±19.15) h·ng·mL⁻¹ vs (114.24±27.11) h·ng·mL⁻¹, AUC_0-∞ (119.52±30.10) h·ng·mL⁻¹ vs (112.04±20.75) h·ng·mL⁻¹, T_max 2.00 h vs 2.00 h, t_1/2 (21.39±3.79) h vs (22.19±4.50) h. The average bioequivalence method indicated that the 90% confidence intervals(CIs) for C_max, AUC_0−t, and AUC_0−∞ under fasting conditions were 97.88%−111.60%, 92.33%−103.60%, and 91.92%−103.61%, respectively. Under fed conditions, the corresponding CIs were 87.63%−101.74%, 88.63%−104.53%, and 88.05%−104.31%, all within the acceptable range of 80%−125%.

CONCLUSION  The test formulation of varenicline tartrate is bioequivalent to the reference formulation under both fasting and fed conditions.