A single-dose, randomized crossover study in healthy Chinese subjects to evaluate pharmacokinetics and bioequivalence of two capsules of calcium dobesilate 0.5 g under fasting and fed conditions

OBJECTIVES: To compare the rate and extent of absorption of a launched generic calcium dobesilate capsule versus the branded reference formulation under fasting and fed conditions in healthy Chinese subjects, and to assess their bioequivalence and tolerability. METHODS: This single-dose, open-label, randomized-sequence, 2-period crossover bioequivalence study was conducted on healthy Chinese volunteers aged 18 to 45 years. Subjects received a single 0.5 g dose of calcium dobesilate capsule under fasting or fed conditions, with a 3-day washout period between doses of the test (T) and reference (R) formulations. Blood samples were collected before and up to 24 hours after administration. The plasma concentration of calcium dobesilate was determined by a validated Liquid chromatography-tandem mass spectrometry method. Non-compartmental analysis was applied to identify the pharmacokinetic (PK) properties. The primary PK parameters including the maximal plasma concentration (C(max)), the area under the plasma concentration-time curve (AUC(0-t)), and the AUC extrapolated to infinity (AUC(0-inf)) were used for bioequivalence evaluation. RESULTS: The mean of PK parameters for T and R capsules under fasting (fed) condition were: C(max), 13.57 (6.71) and 12.59 (7.25) μg/mL; AUC(0-t), 97.32 (79.74) and 96.97 (80.71) h*μg/mL; AUC(0-inf), 101.68 (88.01) and 101.64 (87.81) h*μg/mL. The 90% confidence intervals (CIs) of GMRs under fasting (fed) condition were: C(max), 97.91%-116.62% (88.63%-96.53%); AUC(0-t), 97.15%-104.00% (96.58%-101.39%); and AUC(0-inf), 97.19%-102.89% (98.67%-103.99%). These 90% CIs were all within the bioequivalence range of 80%-125%. All adverse events were mild. CONCLUSION: In this study, the T calcium dobesilate 0.5 g capsule was bioequivalent to the reference product under both fasting and fed conditions. Taking food would slow down its rate and reduce its amount of absorption. Both formulations were generally well tolerated.