Pharmacokinetic and bioequivalence study of enteric-coated omeprazole capsule in healthy Chinese subjects under fasting and fed conditions.

PURPOSE: This study aimed to evaluate the bioequivalence of a generic enteric-coated omeprazole capsule compared with the reference product (Losec®) in healthy Chinese subjects. METHOD: The fasting study was conducted using a randomized, single-centre, single-dose, two-period, two-sequence crossover design. The fed study was a randomized, single-centre, single-dose, four-period, two-sequence fully replicate crossover design. Healthy subjects were randomized and received either the test or the reference drug under fasting or fed conditions. The plasma concentration of enteric-coated omeprazole capsule at different time points was measured using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Bioequivalence of the two formulations was evaluated through pharmacokinetic parameters and relative bioavailability. RESULTS: In the fasting study, the geometric mean ratios (GMRs) of Cmax, AUC0-t, and AUC0-∞ were 101.33%, 101.81%, and 101.76%, respectively, with all 90% confidence intervals (CIs) falling within the bioequivalence range of 80.00-125.00%. Under fed conditions, high intra-subject variability was observed for Cmax (CV = 46.79%) and AUC0-t (CV = 31.61%). The reference-scaled average bioequivalence (RSABE) method showed GMR point estimates of 113.31% for Cmax and 105.68% for AUC0-t (both within 80.00-125.00%), with upper 95% confidence bounds below zero. The GMR for AUC0-∞ was 108.18%, and its 90% CI (102.63-114.02%) also met the bioequivalence criteria. No serious adverse events were reported. CONCLUSION: The two enteric-coated omeprazole capsules were bioequivalent under both fasting and fed conditions and were well tolerated in healthy subjects. TRIAL REGISTRATION: The trial was registered with the China Centre for Drug Testing and Registration ( http://www.chinadrugtrials.org.cn/index.html , 10/05/2022, CTR20221098 and CTR20220627).