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omeprazole
Losec†‡, Prilosec

Pregnancy Risk Category C

How supplied
Capsules (delayed-release):
10 mg, 20 mg, 40 mg

Action
Inhibits activity of acid (proton) pump, and binds to hydrogen-potassium adenosine triphosphatase, located at secretory surface of the gastric parietal cells, to block formation of gastric acid.

Indications & dosage
Symptomatic gastroesophageal reflux
disease (GERD) without esophageal
lesions--

Adults:
20 mg P.O. daily for 4 to 8 weeks for patients poorly responsive to customary medical treatment usually including an adequate course of H2-receptor antagonists.
Erosive esophagitis and accompanying symptoms due to GERD--

Adults:
20 mg P.O. daily for 4 to 8 weeks.
Maintenance of healing erosive esophagitis--

Adults:
20 mg P.O. daily.
Pathologic hypersecretory conditions (such as Zollinger-Ellison syndrome)--

Adults:
initially, 60 mg P.O. daily; dosage adjusted based on patient response. If daily dose exceeds 80 mg, administer in divided doses. Doses up to 120 mg t.i.d. have been given. Continue therapy as long as clinically indicated.
Duodenal ulcer (short-term treatment)--

Adults:
20 mg P.O. daily for 4 to 8 weeks.
Helicobacter pylori infection and duodenal ulcer disease, to eradicate H. pylori with clarithromycin (dual therapy)--
Adults:
40 mg P.O. every morning with clarithromycin 500 mg P.O. t.i.d for days 1 to 14. For patients with an ulcer present at initiation of therapy, an additional 14 days of omeprazole 20 mg P.O. once daily is recommended.
H. pylori infection and duodenal ulcer disease, to eradicate H. pylori with clarithromycin and amoxicillin (triple therapy)--
Adults:
20 mg P.O. with clarithromycin 500 mg P.O. and amoxicillin 1,000 mg P.O., each given b.i.d. for 10 days. For patients with an ulcer present at initiation of therapy, an additional 18 days of omeprazole 20 mg P.O. once daily is recommended.
Short-term treatment of active benign gastric ulcer--

Adults:
40 mg P.O. once daily for 4 to 8 weeks.

Adverse reactions
CNS:
headache, dizziness, asthenia.
GI:
diarrhea, abdominal pain, nausea, vomiting, constipation, flatulence.
Musculoskeletal:
back pain.
Respiratory:
cough, upper respiratory tract infection.
Skin:
rash.

Interactions
Drug-drug.
Ampicillin esters, iron derivatives, ketoconazole: may exhibit poor bioavailability in patients taking omeprazole because optimal absorption of these drugs needs a low gastric pH. Avoid concomitant use.
Diazepam, phenytoin, warfarin:
decreased hepatic clearance, possibly leading to increased serum levels. Monitor closely.
Drug-herb.
Male fern: male fern is inactivated in alkaline environments. Separate administration.
Pennyroyal
: may change rate of formation of toxic metabolites of pennyroyal. Avoid concurrent use.

Effects on diagnostic tests
Serum gastrin levels rise in most patients during the first 2 weeks of therapy.

Contraindications
Contraindicated in patients with hypersensitivity to drug or its components.

Nursing considerations

Patient teaching

*Liquid contains alcohol. **May contain tartrazine.  †Canada  ‡Australia  §U.K.  OTCOver the counter
Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE-THREATENING

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