Bioequivalence Study of Two Olopatadine Hydrochloride Tablets in Chinese Healthy Subjects Under Fasting and Fed Conditions

Abstract Olopatadine hydrochloride, a second‐generation selective histamine H1 receptor antagonist, is an effective anti‐allergic agent. This study evaluated the pharmacokinetics and bioequivalence of two olopatadine hydrochloride tablet formulations in healthy Chinese subjects under fasting (n = 24) and fed (n = 24) conditions. A single‐center, randomized, open‐label, single‐dose, two‐way crossover study was conducted, in which 48 subjects were randomized to receive 5 mg of the test or reference formulation, followed by a 7‐day washout period. Blood samples were collected at predefined intervals up to 24 h post‐dose, and olopatadine plasma concentrations were measured using a validated liquid chromatography‐tandem mass spectrometry method. The results demonstrated no significant differences in the pharmacokinetic profiles between the test and reference formulations under fasting or fed conditions. The 90% confidence intervals (CIs) for the ratio of geometric means of C max , AUC 0–t , and AUC 0–∞ of olopatadine hydrochloride under both conditions were within the bioequivalence range of 0.80–1.25. A high‐fat diet delayed olopatadine hydrochloride absorption, leading to a reduction in C max to approximately 60% of the fasting value and a decrease in AUC to 85%–90%. No serious adverse events occurred, and safety profiles were comparable between formulations. This research confirmed the bioequivalence and similar safety of the generic olopatadine hydrochloride tablets to the reference formulation.