OMEPRAZOLE

OMEPRAZOLE (o-me'pra-zole) Losec , Prilosec, Prilosec OTC, Zegerid Classifications: proton pump inhibitor; Therapeutic: antiulcer; proton pump inhibitor Pregnancy Category: C

Availability

10 mg, 20 mg, 40 mg capsules; 20 mg powder for oral suspension

Action

An antisecretory compound that is a gastric acid pump inhibitor. Suppresses gastric acid secretion by inhibiting the H⁺, K⁺-ATPase enzyme system [the acid (proton H⁺) pump] in the parietal cells.

Therapeutic Effect

Suppresses gastric acid secretion relieving gastrointestinal distress and promoting ulcer healing.

Uses

Duodenal and gastric ulcer. Gastroesophageal reflux disease including severe erosive esophagitis (4 to 8 wk treatment). Long-term treatment of pathologic hypersecretory conditions such as Zollinger-Ellison syndrome, multiple endocrine adenomas, and systemic mastocytosis. In combination with clarithromycin to treat duodenal ulcers associated with Helicobacter pylori.

Unlabeled Uses

Healing or prevention of NSAID-related ulcers.

Contraindications

Long-term use for gastroesophageal reflux disease (GERD), duodenal ulcers; proton pump inhibitors (PPIs), hypersensitivity; children <2 y; use of OTC formulation in children <18 y or GI bleeding; use of Zegerid in metabolic alkalosis, hypocalcemia, vomiting, GI bleeding; pregnancy (category C); lactation.

Cautious Use

Dysphagia; metabolic or respiratory alkalosis; hepatic disease.

Route & Dosage

Gastroesophageal Reflux, Erosive Esophagitis, Duodenal Ulcer Adult: PO 20 mg once/d for 4–8 wk Gastric Ulcer Adult: PO 20 mg b.i.d. for 4–8 wk Hypersecretory Disease Adult: PO 60 mg once/d up to 120 mg t.i.d. Duodenal Ulcer Associated with H. pylori Adult: PO 40 mg once/d for 14 d, then 20 mg/d for 14 d, in combination with clarithromycin 500 mg t.i.d. for 14 d

Administration

Oral

• Give before food, preferably breakfast; capsules must be swallowed whole (do not open, chew, or crush).
• Note: Antacids may be administered with omeprazole.

Adverse Effects (≥1%)

CNS: Headache, dizziness, fatigue. GI: Diarrhea, abdominal pain, nausea, mild transient increases in liver function tests. Urogenital: Hematuria, proteinuria. Skin: Rash.

Diagnostic Test Interference

Omeprazole has been reported to significantly impair peak cortisol response to exogenous ACTH. This finding is undergoing further investigation.

Interactions

Drug: Concomitant administration of diazepam and omeprazole may increase diazepam concentrations. Concomitant administration of phenytoin and omeprazole may increase phenytoin level. Concomitant administration of warfarin and omeprazole may increase warfarin levels. Herbal: Ginkgo, St. John's wort may decrease plasma concentrations.

Pharmacokinetics

Absorption: Poorly from GI tract; 30–40% reaches systemic circulation. Onset: 0.5–3.5 h. Peak: Peak inhibition of gastric acid secretion: 5 d. Metabolism: In liver. Elimination: 80% in urine, 20% in feces. Half-Life: 0.5–1.5 h.

Nursing Implications

Assessment & Drug Effects

• Lab tests: Monitor urinalysis for hematuria and proteinuria. Periodic liver function tests with prolonged use.

Patient & Family Education

• Report any changes in urinary elimination such as pain or discomfort associated with urination, or blood in urine.
• Report severe diarrhea; drug may need to be discontinued.

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Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug