Omeprazole (H 16868), a proton pump inhibitor (PPI), is available for treatment of acid-related gastrointestinal disorders. Omeprazole shows competitive inhibition of CYP2C19 activity with a Ki of 2 to 6 μM[1]. Omeprazole also inhibits growth of Gram-positive and Gram-negative bacteria[2].

Omeprazole (H 16868) is a proton pump inhibitor used in the treatment of dyspepsia, peptic ulcer disease, gastroesophageal reflux disease, laryngopharyngeal reflux, and Zollinger-Ellison syndrome. Omeprazole (H 16868) virtually eliminated intragastric acidity in all patients: the median 24 hour intragastric pH rose from 1.4 to 5.3 and the mean hourly hydrogen ion activity fell from 38.50 to 1.95 mmol(mEq)/1 (p less than 0.001). This inhibition of 24 hour intragastric acidity is more profound than that previously reported with either cimetidine 1 g daily or ranitidine 300 mg daily[1]. The pharmacokinetics of omeprazole were studied in a group of healthy male subjects after single and repeated oral doses of 30 and 60 mg. Absorption of Omeprazole (H 16868) from its enteric-coated formulation was unpredictable. There was a highly significant increase in the area under the plasma concentration time curve (AUC) after repeated dosing. Omeprazole (H 16868) increases its own relative availability following repeated dosing. This may be due to inhibition of gastric acid secretion by omeprazole which is an acid-labile compound[2].

References:
[1]. Li XQ, et al. Comparison of inhibitory effects of the proton pump-inhibiting drugs omeprazole, esomeprazole, lansoprazole, pantoprazole, and rabeprazole on human cytochrome P450 activities. Drug Metab Dispos. 2004 Aug;32(8):821-7.
[2]. Jonkers D, et al. Omeprazole inhibits growth of gram-positive and gram-negative bacteria including Helicobacter pylori in vitro. J Antimicrob Chemother. 1996 Jan;37(1):145-50.