Omeprazole esomeprazole

The histamine2-receptor antagonists or H2RAs (cimetidine, famotidine, nizatidine, and ranitidine) and proton pump inhibitors (omeprazole, esomeprazole, lansoprazole, pantopra-zole, and rabeprazole) reduce the amount of acid secreted into the stomach by gastric parietal cells. These agents are also helpful for nausea and vomiting related to gastric acid secretion. 

Proton pump inhibitors (PPIs), such as omeprazole, esomeprazole, lansoprazole, pantoprazole, and rabeprazole, are commonly prescribed to treat symptoms of heartburn, acid reflux, chest pain, dyspepsia, and chronic cough. PPIs inhibit the transfer of protons into the stomach lumen. Pharmacological acid suppression is thus used to treat gastroesophageal reflux disease (GERD) and esophagitis, peptic ulcers, and Helicobacter pylori infection as well as to prevent ulcer development with concurrent nonsteroidal anti-inflammatory drug use. 

Li XQ, Andersson TB, Ahlstrom M, et al. Comparison of inhibitory effects of the proton pump-inhibiting drugs omeprazole, esomeprazole, lansoprazole, pan-toprazole, and rabeprazole on human cytochrome P450 activities. Drug Metab Dispos 2004 32 821-827. 

Pharmacokinetics (PK) and effect on pentagastrin-stimulated peak acid output (PAO) of omeprazole (O) and its two optical isomers, S-omeprazole/esomeprazole (E) and R-omeprazole (R-O). Reproduced with permission from the American Gastroenterological Association. 

Omeprazole (p. 171) can cause maximal inhibition of HC1 secretion. Given orally in gastric juice-resistant capsules, it reaches parietal cells via the blood. In the acidic milieu of the mucosa, an active metabolite is formed and binds covalently to the ATP-driven proton pump (H+/K+-ATPase) that transports H+ in exchange for I<+ into the gastric juice. Lansoprazole, pantoprazole, and rabeprazole produce analogous effects. Omeprazole is a racemate. With respect to dosage, the now available (S)-omeprazole (esomeprazole) represents the more potent enantiomer, but this offers no therapeutic advantage. 

MOCLOBEMIDE PROTON PUMP INHIBITORS -OMEPRAZOLE/ ESOMEPRAZOLE Possible t efficacy and adverse effects of modobemide Inhibition of CYP2C19 Monitor more closely effect only seen in extensive CYP2C19 metabolizers. Dose i may be required... 

BZDs PROTON PUMP INHIBITORS -OMEPRAZOLE/ ESOMEPRAZOLE T efficacy and adverse effects, e.g. prolonged sedation Inhibition of metabolism via CYP4S0 (some show competitive inhibition via CYP2C19) Monitor for t side-effects, and 1 dose as necessaiy. Likely to delay recovery after procedures for which BZDs have been used. Consider alternative proton pump inhibitor, e.g. lansoprazole or pantoprazole... 

Until recently, all PPIs were marketed as mixtures of enantiomers. However, the development of esomeprazolehas prompted numerous studies to test its therapeutic benefit over that of existing PPIs. Within the last 2 years mae than 40 publications have reported studies involving the use of esomeprazole. Es-omeprazole has an improved pharmacokinetic profile relative to that of omeprazole esomeprazole (20 mg per day for 5 days) had a 70% higher area under the plasma concentrationtime curve than that of omeprazole (20 mg per day for 5 days). The S-isomer of omeprazole (esomeprazole) was found to undergo less metabolism by CYP2C19 than the R-isomer in human liver, this decreased metabolism ac-... 

The PPIs (omeprazole, esomeprazole, lansoprazole, rabeprazole, and pantoprazole) dose-dependently inhibit basal and stimulated gastric acid secretion. When PPI therapy is initiated, the degree of acid suppression increases over the first 3 to 4 days of therapy, as more and more proton pumps are inhibited. Upon discontinuation of therapy, full restoration of acid secretion takes 3 to 5 days. Because PPIs inhibit only those proton pumps that are actively secreting acid, they are most effective when taken 15 to 30 minutes before meals. ... 

Later on, one of the single enantiomers of omeprazole, esomeprazole, was selected as a CD. This may seem strange and poses the question as to why had the single enantiomers not been investigated at an earlier stage Omeprazole displays... 

To prevent degradation of proton-pump inhibitors by acid in the gastric lumen, oral dosage forms are supplied in different formulations (1) enteric-coated drugs contained inside gelatin capsules (omeprazole, esomeprazole, and... 

The bioavailability of ketoconazole is reduced by both omeprazole and rabeprazole. Other proton pump inhibitors are expected to behave similarly. Omeprazole also markedly reduces the absorption of itraconazole capsules, but not the oral solution. Proton pump inhibitors are predicted to reduce the bioavailability of posaconazole. The bioavailabilities of fluconazole and voriconazole are not significantly affected by omeprazole. Esomeprazole levels may also be Increased by voriconazole.Omeprazole levels are Increased by ketoconazole, and markedly increased by fluconazole and voriconazole. 

The pharmacokinetic interactions between clarithromycin and omeprazole, esomeprazole and lansoprazole are established. However, none of the changes reported represents an adverse interaction, but they may help to explain why concurrent use is valuable in the eradication of Helicobacter pylori. Erythromycin is likely to interact similarly, whereas roxithromycin does not. Pantoprazole is not affected by macrolides. 

To achieve a longer plasma half-life, an enantiomer of omeprazole has been introduced S-omeprazole, esomeprazole. These structures are shown in the figure. This has a slower metabolism than the R-enantiomer and therefore appears to have a longer dwell time in the blood. At 40-mg dosage, there appears to be improvement in pH control as compared to omeprazole as shown in the figure. 

More recently, pantoprazole has been introduced in an IV formulation. It is inherently more acid stable than omeprazole, esomeprazole, or lansoprazole, and hence does not require a highly alkaline buffer for reconstitution. 

Hassan-Alin, M., T. Andersson, M. Niazi, and K. Roehss, A pharmacokinetic study comparing single and repeated oral doses of 20 mg and 40 mg omeprazole and its two optical isomers, S-omeprazole (esomeprazole)... 

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