Abstract
Study background: Omeprazole is indicated for the treatment of various acid-related gastrointestinal disorders. It is acid labile and therefore administered orally as enteric-coated granules in capsules. Methods: This randomized, open-label, single dose, two-way cross-over clinical pharmacology study in healthy adult Filipino subjects evaluated the bioequivalence of a new 40 mg delayed-release (enteric-film coated) capsule formulation of omeprazole (Pfizer Inc., US) relative to the reference marketed Losec® capsule (2x20 mg; AstraZeneca, Sweden; enteric-coated granules in capsule) under fasted conditions. Pharmacokinetic blood sampling was carried out at various time points for 12 h post-dose and plasma samples were analysed using a fully validated ultra performance liquid chromatography with tandem Mass Spectrometry technology. The primary endpoints were area under plasma concentration-time curve (AUC) from time zero to the time of the last quantifiable concentration (AUClast) and maximum plasma concentration (Cmax) for omeprazole. Results: Twenty five subjects (12 females and 13 males; mean age 26 years; mean body mass index 24 kg/ m2) completed the study. When administered as one omeprazole 40 mg delayed-release capsule, the ratios of the adjusted geometric means of the primary endpoints, AUClast and Cmax, were contained within the established bioequivalence limits of 80 to 125% compared with two Losec® 20 mg capsules: 100.4% (90% confidence interval: 90.8–110.9%) and 90.4% (90% confidence interval: 81.2–100.6%), respectively. The two omeprazole formulations were well tolerated and no serious adverse event or other significant adverse event was noted. Conclusion: Based on the results of this study in healthy adult Filipino subjects, the new omeprazole 40 mg delayed-release capsule and the established marketed Losec® capsule (2x20 mg) are bioequivalent. Omeprazole 40 mg delayed-release capsule was safe and well tolerated.
Highlights
Omeprazole is a lipophilic weak base that is converted to its active protonated form in the highly acidic environment of the intracellular canaliculi within the parietal cells of the stomach [1,2]
Twenty five subjects completed the study and were included in the PK analyses; one subject was withdrawn after dosing with Losec® (Reference) treatment during the second treatment period due to an adverse event (AE)
Total exposures (AUClast and AUCinf) of omeprazole were similar for both formulations: single-dose administration of the 40 mg delayed-release capsule and 40 mg (2 x 20 mg) Losec® (Table 1)
Summary
Omeprazole is a lipophilic weak base that is converted to its active protonated form in the highly acidic environment of the intracellular canaliculi within the parietal cells of the stomach [1,2]. It blocks the final step in gastric acid production through specific irreversible inhibition of the gastric proton pump (H+/K+-ATPase) in the parietal cells [1,2]. This provides for highly effective inhibition of both basal acid secretion and stimulated acid secretion. The elimination half-life in plasma is usually
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