indication

For the treatment of acid-reflux disorders (GERD), peptic ulcer disease, H. pylori eradication, and prevention of gastroinetestinal bleeds with NSAID use.

pharmacology

Omeprazole is a compound that inhibits gastric acid secretion and is indicated in the treatment of gastroesophageal reflux disease (GERD), the healing of erosive esophagitis, and H. pylori eradication to reduce the risk of duodenal ulcer recurrence. Omeprazole belongs to a new class of antisecretory compounds, the substituted benzimidazoles, that do not exhibit anticholinergic or H2 histamine antagonistic properties, but that suppress gastric acid secretion by specific inhibition of the H⁺/K⁺ ATPase at the secretory surface of the gastric parietal cell. As a result, it inhibits acid secretion into the gastric lumen. This effect is dose-related and leads to inhibition of both basal and stimulated acid secretion irrespective of the stimulus.

mechanism of action

Omeprazole is a proton pump inhibitor that suppresses gastric acid secretion by specific inhibition of the H⁺/K⁺-ATPase in the gastric parietal cell. By acting specifically on the proton pump, omeprazole blocks the final step in acid production, thus reducing gastric acidity.

toxicity

Symptoms of overdose include confusion, drowsiness, blurred vision, tachycardia, nausea, diaphoresis, flushing, headache, and dry mouth.

biotransformation

Hepatic.

absorption

Absorption is rapid, absolute bioavailability (compared to intravenous administration) is about 30-40% at doses of 20-40 mg.

half life

0.5-1 hour

route of elimination

Urinary excretion is a primary route of excretion of omeprazole metabolites.

drug interactions

Alprazolam: Omeprazole may increase the effect of the benzodiazepine, alprazolam.

Atazanavir: This gastric pH modifier decreases the levels/effects of atazanavir

Cefditoren: Proton pump inhibitors such as omeprazole may decrease the serum concentration of cefditoren. If possible, avoid use of cefditoren with proton pump inhibitors (PPIs). Consider alternative methods to minimize/control acid reflux (eg, diet modification) or alternative antimicrobial therapy if use of PPIs can not be avoided.

Chlordiazepoxide: Omeprazole may increase the effect of the benzodiazepine, chlordiazepoxide.

Cilostazol: Omeprazole increases the effect of cilostazol

Clonazepam: Omeprazole may increase the effect of the benzodiazepine, clonazepam.

Clopidogrel: Omeprazole may decrease serum concentrations of the active metabolite(s) of clopidogrel. Clopidogrel prescribing information recommends avoiding concurrent use with omeprazole, due to the possibility that combined use may result in decreased clopidogrel effectiveness.

Clorazepate: Omeprazole may increase the effect of the benzodiazepine, clorazepate.

Cyclosporine: Omeprazole increases the effect and toxicity of cyclosporine

Dasatinib: Omeprazole may decrease the serum level of dasatinib.

Diazepam: Omeprazole may increase the effect of the benzodiazepine, diazepam.

Disopyramide: The beta-blocker increases toxicity of disopyramide

Enoxacin: Omeprazole may decrease the absorption of enoxacin.

Estazolam: Omeprazole may increase the effect of the benzodiazepine, estazolam.

Ethotoin: Omeprazole increases the effect of hydantoin

Flurazepam: Omeprazole may increase the effect of the benzodiazepine, flurazepam.

Fosphenytoin: Omeprazole increases the effect of hydantoin

Halazepam: Omeprazole may increase the effect of the benzodiazepine, halazepam.

Indinavir: Omeprazole decreases the absorption of indinavir

Itraconazole: The proton pump inhibitor, omeprazole, may decrease the absorption of itraconazole.

Ketazolam: Omeprazole may increase the effect of the benzodiazepine, ketazolam.

Ketoconazole: The proton pump inhibitor, omeprazole, may decrease the absorption of ketoconazole.

Mephenytoin: Omeprazole increases the effect of hydantoin

Methotrexate: Omeprazole increases the levels of methotrexate

Midazolam: Omeprazole may increase the effect of the benzodiazepine, midazolam.

Phenytoin: Omeprazole increases the effect of hydantoin

Prazepam: Omeprazole may increase the effect of the benzodiazepine, prazepam.

Quazepam: Omeprazole may increase the effect of the benzodiazepine, quazepam.

St. John's Wort: St. John's Wort decreases the levels/effects of omeprazole

Tacrolimus: Omeprazole may increase the blood concentration of Tacrolimus. Monitor for changes in the therapeutic/toxic effects of Tacrolimus if Omeprazole therapy is initiated, discontinued or altered.

Tipranavir: Tipranavir, co-administered with Ritonavir, may decrease the plasma concentration of Omeprazole. Consider alternate therapy or increase the dose of Omeprazole based on the therapeutic response.

Triazolam: Omeprazole may increase the effect of the benzodiazepine, triazolam.

Trimipramine: The strong CYP2C19 inhibitor, Omeprazole, may decrease the metabolism and clearance of Trimipramine, a CYP2C19 substrate. Consider alternate therapy or monitor for changes in therapeutic and adverse effects of Trimipramine if Omeprazole is initiated, discontinued or dose changed.

Voriconazole: Voriconazole increases the effect and toxicity of omeprazole