General

Pronunciation
o-MEP-ra-zole

Trade Name(s)

• Losec [Canada]

• Prilosec

• Prilosec OTC

Pregnancy Category
Category C

Ther. class.
antiulcer agents

Pharm. class.
proton pump inhibitors

Indications

• GERD/maintenance of healing in erosive esophagitis

• Duodenal ulcers (with or without anti-infectives for Helicobacter pylori )

• Short-term treatment of active benign gastric ulcer

• Pathologic hypersecretory conditions, including Zollinger-Ellison syndrome

• Reduction of risk of GI bleeding in critically ill patients

• OTC: Heartburn occurring Btwice/wk

Action

Binds to an enzyme on gastric parietal cells in the presence of acidic gastric pH, preventing the final transport of hydrogen ions into the gastric lumen

Therapeutic Effect(s):

• Diminished accumulation of acid in the gastric lumen with lessened gastroesophageal reflux

• Healing of duodenal ulcers

Pharmacokinetics

Absorption: Rapidly absorbed following oral administration; immediate release formulation contains bicarbonate to prevent acid degradation

Distribution: Good distribution into gastric parietal cells

Protein Binding: 95%

Metabolism and Excretion: Extensively metabolized by the liver

Half-life: 0.5–1 hr (↑ in liver disease to 3 hr)

TIME/ACTION PROFILE (antisecretory effects)

ROUTE	ONSET	PEAK	DURATION
PO-delayed release	within 1 hr	within 2 hr	72–96 hr

Contraindication/Precautions

Contraindicated in:

• Hypersensitivity

• Lactation: Discontinue omeprazole or discontinue breastfeeding

Use Cautiously in:

• Liver disease (dose ↓ may be necessary)

• OB: Lactation: Pedi: Safety not established in pregnant or breastfeeding women, or children <1 yr

• Geri: ↑ risk of hip fractures in patients using high doses for >1 year

Adverse Reactions/Side Effects

CNS: dizziness, drowsiness, fatigue, headache, weakness.

CV: chest pain.

GI: abdominal pain, acid regurgitation, constipation, diarrhea, flatulence, nausea, vomiting.

Derm: itching, rash.

Misc: allergic reactions.

*CAPITALS indicates life-threatening.
*italic indicates most frequent.

Interactions

Drug-Drug

• Omeprazole is metabolized by the CYP450 enzyme system and may compete with other agents metabolized by this system

• ↓ metabolism and may ↑ effects of antifungal agents , diazepam , digoxin , flurazepam , triazolam , cyclosporine , phenytoin , saquinavir , tacrolimus , and warfarin

• May ↓ absorption of drugs requiring acid pH, including ketoconazole , itraconazole , ampicillin , iron salts , and digoxin

• Has been used safely with antacids

• May significantly ↓ effects of atazanavir and nelfinavir (concurrent use not recommended)

• May ↑ risk of bleeding with warfarin (monitor INR/PT)

• May ↓ the antiplatelet effects of clopidogrel

Route/Dosage

• PO (Adults): GERD/erosive esophagitis—20 mg once daily. Duodenal ulcers associated with H. pylori—40 mg once daily in the morning with clarithromycin for 2 wk, then 20 mg once daily for 2 wk or 20 mg twice daily with clarithromycin 500 mg twice daily and amoxicillin 1000 mg twice daily for 10 days (if ulcer is present at beginning of therapy, continue omeprazole 20 mg daily for 18 more days); has also been used with clarithromycin and metronidazole. Gastric ulcer—40 mg once daily for 4–6 wk. Reduction of the risk of GI bleeding in critically ill patients—40 mg initially, then another 40 mg 6–8 hr later, followed by 40 mg once daily for up to 14 days. Gastric hypersecretory conditions—60 mg once daily initially; may be increased up to 120 mg 3 times daily (doses >80 mg/day should be given in divided doses); OTC—20 mg once daily for up to 14 days.

• PO (Children 1–16 yr and 5–9 kg): GERD/erosive esophagitis—5 mg once daily.

• PO (Children 1–16 yr and 10–19 kg): GERD/erosive esophagitis—10 mg once daily.

• PO (Children 1–16 yr and B20 kg): GERD/erosive esophagitis—20 mg once daily.

Availability

• Delayed-release capsules: 10 mg, 20 mg^{Rx, OTC}, 40 mg

• Delayed-release powder for oral suspension (peach-mint): 2.5 mg/packet, 10 mg/packet

• In combination with: metronidazole and clarithromycin in a compliance package (Losec 1-2-3 M); with amoxicillin and clarithromycin in a compliance package (Losec 1-2-3-A) (both in Canada only); with sodium bicarbonate (Zegerid; see combination drugs)

Assessment

• Assess patient routinely for epigastric or abdominal pain and frank or occult blood in the stool, emesis, or gastric aspirate

Lab Test Considerations

• Monitor CBC with differential periodically during therapy

» May cause ↑ AST, ALT, alkaline phosphatase, and bilirubin

» May cause serum gastrin concentrations to ↑ during first 1–2 wk of therapy. Levels return to normal after discontinuation of omeprazole

» Monitor INR and prothrombin time in patients taking warfarin

Potential Nursing Diagnoses

• Acute pain (Indications)

Implementation

• Do not confuse Prilosec (omeprazole) with Prinivil (lisinopril)

• PO: Administer doses before meals, preferably in the morning. Capsules should be swallowed whole; do not crush or chew. Capsules may be opened and sprinkled on cool applesauce, entire mixture should be ingested immediately and followed by a drink of water. Do not store for future use

» Powder for oral suspension: Administer on empty stomach, as least 1 hr before a meal. For patients with nasogastric or enteral feeding, suspend feeding for 3 hr before and 1 hr after administration. Empty packet contents into a small cup containing 1–2 tablespoons of water. Do not use other liquids or foods. If administered through a nasogastric tube, suspend in 20 mL of water. Stir well and drink immediately. Refill cup with water and drink again

» May be administered concurrently with antacids

Patient/Family Teaching

• Instruct patient to take medication as directed for the full course of therapy, even if feeling better. Take missed doses as soon as remembered but not if almost time for next dose. Do not double doses

• May cause occasional drowsiness or dizziness. Caution patient to avoid driving or other activities requiring alertness until response to medication is known

• Advise patient to consult health care professional before taking any Rx, OTC, or herbal products with omeprazole

• Advise patient to avoid alcohol, products containing aspirin or NSAIDs, and foods that may cause an increase in GI irritation

• Advise patient to report onset of black, tarry stools; diarrhea; abdominal pain; or persistent headache to health care professional promptly

Evaluation/Desired Outcomes

• Decrease in abdominal pain or prevention of gastric irritation and bleeding. Healing of duodenal ulcers can be seen on x-ray examination or endoscopy

• Decrease in symptoms of GERD and erosive esophagitis. Therapy is continued for 4–8 wk after initial episode

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