Brand names: PriLOSEC, Talicia
Drug class: Proton-pump Inhibitors

Medically reviewed by Drugs.com on May 10, 2025. Written by ASHP.

Introduction

Acid- or proton-pump inhibitor (PPI); gastric antisecretory agent.

Uses for Omeprazole

Duodenal Ulcer

Short-term treatment of active duodenal ulcer in adults. Most patients heal within 4 weeks; some patients may require an additional 4 weeks of therapy.

Treatment of Helicobacter pylori infection and duodenal ulcer disease (active or up to 1 year history) in adults. Used in conjunction with amoxicillin and clarithromycin (triple therapy) or clarithromycin (dual therapy); a co-packaged product containing delayed-release omeprazole capsules, clarithromycin tablets, and amoxicillin capsules (Omeclamox-Pak) is also used for this indication. Has been used in other multidrug regimens^{† [off-label]}.

Also available in fixed combination with amoxicillin and rifabutin (Talicia) for treatment of H. pylori in adults. See full prescribing information for use of this combination product. Current guidelines from the ACG do not recommend dual or triple therapy PPI regimens containing clarithromycin for first-line treatment of H. pylori due to increasing prevalence of clarithromycin resistance in clinical practice.

Gastric Ulcer

Short-term (4–8 week) treatment of active benign gastric ulcer in adults.

Gastroesophageal Reflux Disease (GERD)

Short-term treatment of symptomatic GERD (e.g., heartburn).

Short-term self-medication for symptomatic relief of frequent (e.g., 2 or more days a week) heartburn in adults; not intended for immediate heartburn relief since may take 1–4 days for full effect.

Guidelines recommend a 4- or 8-week trial of once-daily PPI therapy for initial management of GERD symptoms (i.e., heartburn, regurgitation, non-cardiac chest pain) without alarm symptoms (e.g., dysphagia, weight loss, GI bleeding). Patients with inadequate response to once-daily PPI can be increased to twice-daily dosing or switched to a more effective acid suppressant. Once adequate response achieved, discontinue PPI therapy.

Erosive Esophagitis

Short-term treatment (4–8 weeks) of erosive esophagitis (endoscopically diagnosed) in patients with acid-mediated GERD.

Maintain healing and decrease recurrence of erosive esophagitis due to acid-mediated GERD. Controlled studies do not extend beyond 12 months' duration.

In patients who experience incomplete symptom relief or symptom recurrence following trial of PPI therapy for GERD, endoscopy is recommended. PPI therapy should be optimized in patients with evidence of erosion (i.e., Los Angeles A-D esophagitis), and may be continued indefinitely in patients with more severe disease.

Pathologic Hypersecretory Conditions

Long-term treatment of pathologic hypersecretory conditions (e.g., Zollinger-Ellison syndrome, multiple endocrine adenomas, systemic mastocytosis) in adults.

Upper GI Bleeding

Used to decrease risk of upper GI bleeding in critically ill patients.

Omeprazole Dosage and Administration

General

Pretreatment Screening

• Consider monitoring magnesium and calcium levels prior to initiating omeprazole in patients with a preexisting risk for hypocalcemia (e.g., hypoparathyroidism).

• In patients expected to receive long-term therapy with a PPI or in those receiving a PPI concomitantly with digoxin or drugs that may cause hypomagnesemia (e.g., diuretics), consider measurement of serum magnesium concentrations prior to initiating PPI therapy.

Patient Monitoring

• In patients expected to receive long-term PPI therapy or in those receiving a PPI concomitantly with digoxin or drugs that may cause hypomagnesemia (e.g., diuretics), consider periodic monitoring of serum magnesium concentrations.

• Consider periodic monitoring of magnesium and calcium levels in patients with a preexisting risk for hypocalcemia (e.g., hypoparathyroidism) during omeprazole therapy.

Dispensing and Administration Precautions

• The Institute for Safe Medication Practices (ISMP) includes omeprazole and fomepizole on their ISMP List of Confused Drug Names, and recommends using special safeguards to ensure the accuracy of prescriptions for these drugs.

• The 2023 American Geriatrics Society (AGS) Beers Criteria for Potentially Inappropriate Medication (PIM) Use in Older Adults includes omeprazole on the list of PIMs that are best avoided by older adults in most circumstances or under specific situations, such as certain diseases, conditions, or care settings. The criteria are intended to apply to adults 65 years of age and older in all ambulatory, acute, and institutional settings of care, except hospice and end-of-life care settings. For proton-pump inhibitors including omeprazole, the Beers Criteria Expert Panel recommends that scheduled use for more than 8 weeks generally be avoided with certain exceptions.

Other General Considerations

• The sodium content of omeprazole preparations containing sodium bicarbonate should be taken into consideration in patients whose sodium intake must be restricted or in those at risk for congestive heart failure.

Administration

Available as delayed-release and immediate-release capsules and oral suspension.

A co-packaged product containing delayed-release omeprazole capsules, clarithromycin tablets, and amoxicillin capsules (Omeclamox-Pak) is also commercially available.

Omeprazole magnesium is also available in fixed-combination capsules containing amoxicillin and rifabutin (Talicia).

Omeprazole is acid-labile. To avoid decomposition in acidic pH of the stomach, delayed-release capsules and delayed-release oral suspension contain enteric-coated granules of the drug. Immediate-release capsules, oral suspension, and kit for oral suspension (Konvomep) all contain sodium bicarbonate to protect the drug.

Oral Administration

Immediate-release Capsules

Swallow intact with a glass of water ≥1 hour prior to a meal. Do not use with any other liquid. Do not open capsules or mix the contents with food.

Do not substitute two 20-mg capsules for one 40-mg capsule because the 20-mg and 40-mg capsules contain the same amount of sodium bicarbonate.

Delayed-release Capsules

Administer orally at least 1 hour before a meal.

Swallow capsules intact; do not chew or crush.

Antacids may be used concomitantly as needed for pain relief.

Alternatively, open capsule and mix contents with 1 tablespoon applesauce; swallow immediately without chewing and with a glass of cool water to ensure complete swallowing. Applesauce should not be hot and should be soft enough to swallow without chewing.

Powder for Immediate-release Oral Suspension

Administer at least 1 hour prior to a meal.

Empty 20- or 40-mg single-dose packet for oral suspension into small cup containing 5–10 mL of water, stir well, and swallow immediately. Rinse container with more water and swallow to ensure complete consumption of the dose. Do not mix with any other liquid or food.

Do not substitute two 20-mg packets for one 40-mg packet because the 20- and 40-mg powder for oral suspension packets contain the same amount of sodium bicarbonate.

Powder for Delayed-release Oral Suspension

Administer at least 1 hour before a meal.

Antacids may be used concomitantly.

Empty contents of 2.5- or 10-mg single-dose packet into small cup containing 5 or 15 mL, respectively, of water. Stir well, then allow to thicken for 2–3 minutes. Stir again and administer within 30 minutes of preparation. If any material remains in the cup, add additional water, mix, and ingest immediately to ensure complete consumption of the dose.

Powder Kit for Oral Suspension

Reconstitute Konvomep before administration.

Prior to reconstitution, tap bottom of the powder bottle on hard surface to loosen powder; add approximately one-third of diluent to powder bottle and shake for approximately 30 seconds. Then add second one-third of diluent to powder bottle and shake vigorously for approximately 30 seconds. Add remainder of diluent bottle to powder bottle and shake vigorously for approximately 30 seconds. Final concentration of reconstituted suspension is 40 mg/20 mL (2 mg/mL) of omeprazole and 84 mg/mL of sodium bicarbonate.

NG Tube

Powder for delayed-release oral suspension: Reconstitute 2.5- or 10-mg single-dose packet with 5 or 15 mL of water, respectively, in a catheter-tipped syringe and shake immediately. Allow mixture to thicken for 2–3 minutes. Shake syringe and administer within 30 minutes through NG or gastric tube (6 French or larger). Refill syringe with additional water (5 or 15 mL, respectively), shake, and flush any remaining drug mixture from the tube.

Powder for immediate-release oral suspension: Reconstitute 20- or 40-mg single-dose packet with 20 mL of water, stir well, administer immediately through NG or orogastric tube using appropriately sized syringe. Flush the tube with 20 mL of water after administration. Temporarily stop continuous enteral feeding via NG or orogastric tube for 3 hours before and 1 hour after administration.

Powder kit for oral suspension (Konvomep): Shake oral suspension well before dispensing into a catheter or oral tip syringe. Immediately inject mixture through NG or orogastric tube (8 French or larger). Flush the tube with 20 mL of water after administration. Temporarily stop continuous enteral feeding via NG or orogastric tube for 3 hours before and 1 hour after administration.

Dosage

Available as omeprazole and omeprazole magnesium; dosage expressed in terms of omeprazole.

Pediatric Patients

GERD

Oral (Delayed-release Suspension)

See Table 1 for recommended dosage for pediatric patients 1–16 years of age. Dosage administered for up to 4 weeks for symptomatic GERD.

Oral (Delayed-release Capsules)

See Table 2 for recommended dosage for pediatric patients 2–16 years of age. Administered for up to 4 weeks for symptomatic GERD.

Erosive Esophagitis

Oral (Delayed-release Suspension)

See Table 3 for recommended dosage for treatment in pediatric patients 1 month to <1 year of age. For short-term treatment up to 6 weeks.

See Table 4 for recommended dosage for treatment in pediatric patients 1–16 years of age. For short-term treatment (4-8 weeks) in patients ≥1 year of age; an additional 4 weeks (up to 12 weeks for a single course) may be considered in patients ≥1 year of age.

See Table 5 for recommended dosage for maintenance therapy (maintenance of healing) in pediatric patients 1–16 years of age. Safety and efficacy of maintenance therapy for longer than 1 year not established.

Oral (Delayed-release Capsules)

See Table 6 for recommended dosage for treatment in pediatric patients 2–16 years of age. For short-term treatment (4-8 weeks); an additional 4 weeks (up to 12 weeks for a single course) may contribute to healing and symptomatic improvement in some patients.

See Table 7 for recommended dosage for maintenance therapy (maintenance of healing) in pediatric patients 2–16 years of age. Safety and efficacy of maintenance therapy for longer than 1 year not established.

Adults

Duodenal Ulcer

Oral (Immediate-release Capsules or Suspension; Delayed-release Capsules or Suspension)

Treatment of active duodenal ulcer: 20 mg once daily until healing occurs (usually within 4 weeks); an additional 4 weeks of therapy may be beneficial in some patients.

Oral (Delayed-release Capsules or Suspension)

Triple therapy for treatment of Helicobacter pylori infection and active duodenal ulcer: 20 mg twice daily (morning and evening) for 10 days in conjunction with amoxicillin and clarithromycin; additional omeprazole therapy with 20 mg once daily for 18 days recommended if active ulcer present initially.

Dual therapy for treatment of Helicobacter pylori infection and active duodenal ulcer: 40 mg once daily (in the morning) for 14 days in conjunction with clarithromycin; omeprazole 20 mg once daily for additional 14 days recommended if active ulcer present initially.

Erosive Esophagitis

Oral (Immediate-release Capsules or Suspension; Delayed-release Capsules or Suspension)

Treatment of erosive esophagitis due to acid-mediated GERD: 20 mg once daily until healing occurs (usually within 4–8 weeks). May give an additional 4 weeks of therapy (up to 12 weeks for a single course). If recurs, consider additional 4–8 weeks of therapy.

Oral (Immediate-release Capsules or Suspension; Delayed-release Capsules or Suspension)

Maintenance of healing of erosive esophagitis: 20 mg once daily. Safety and efficacy of omeprazole maintenance therapy for longer than 1 year have not been established.

Gastric Ulcer

Oral (Immediate-release Capsules or Suspension; Delayed-release Capsules or Suspension)

Short-term treatment of active benign gastric ulcer: 40 mg once daily for 4–8 weeks.

GERD

Oral (Immediate-release Capsules or Suspension; Delayed-release Capsules or Suspension)

Symptomatic GERD without erosive esophageal lesions: 20 mg once daily for up to 4 weeks.

For self-medication to relieve symptoms of frequent heartburn in adults, an omeprazole dosage of 20 mg once daily in the morning for 14 days is recommended. The 14-day course of therapy may be repeated every 4 months, if needed.

Pathologic Hypersecretory Conditions (e.g., Zollinger-Ellison Syndrome, Multiple Endocrine Adenomas, Systemic Mastocytosis)

Oral (Delayed-release Capsules or Suspension)

60 mg once daily initially. Adjust dosage according to patient response and tolerance; continue therapy as long as necessary. Administer daily dosages >80 mg in divided doses.

Dosages of up to 360 mg daily (given in 3 divided doses) have been used.

Has been given continuously for >5 years in some patients with Zollinger-Ellison syndrome.

Upper GI Bleeding

Oral (Immediate-release Suspension)

Reduction of risk of upper GI bleeding in critically ill adults: Initially, 40 mg followed by 40 mg after 6–8 hours on the first day, then 40 mg once daily for 14 days. Safety and efficacy for >14 days not established.

Special Populations

Hepatic Impairment

Delayed-release capsules or delayed-release oral suspension: Dosage reduction to 10 mg once daily recommended in patients receiving omeprazole for maintenance of healing of erosive esophagitis.

Immediate-release capsules or immediate-release oral suspension: Not recommended for use in patients with hepatic impairment (Child-Pugh class A, B, or C) when used for maintenance of healing of erosive esophagitis.

Manufacturer recommends avoiding use of Omeclamox-Pak in patients with hepatic impairment.

Renal Impairment

Although bioavailability slightly increases in patients with chronic renal impairment (Cl_cr 10–62 mL/minute per 1.73m²), manufacturers state dosage adjustment not necessary.

Geriatric Patients

No dosage adjustment necessary.

Asian Patients

Delayed-release capsules or delayed-release oral suspension: Dosage reduction to 10 mg once daily recommended in patients receiving omeprazole therapy for maintenance of healing of erosive esophagitis.

Immediate-release capsules or immediate-release oral suspension: Not recommended for use in Asian patients when used for maintenance of healing of erosive esophagitis.

Manufacturer recommends avoiding use of Omeclamox-Pak in Asian patients unless benefits outweigh risks.

Pharmacogenomic Considerations

Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines recommend initiation of standard PPI dosages in patients who are CYP2C19 likely intermediate metabolizers (e.g., CYP2C19*1/*9, CYP2C19*9/*17, CYP2C19*9/*9), intermediate metabolizers (e.g., CYP2C19*1/*2, CYP2C19*1/*3, CYP2C19*2/*17, CYP2C19*3/*17), likely poor metabolizers (e.g., CYP2C19*2/*9 or CYP2C19*3/*9), or poor metabolizers (e.g., CYP2C19*2/*2, CYP2C19*3/*3, CYP2C19*2/*3); however, for chronic therapy exceeding 12 weeks, consider a 50% reduction in daily dosage with monitoring for continued efficacy.

Standard PPI dosages may be initiated in patients who are CYP2C19 rapid metabolizers (e.g., CYP2C19*1/*17) or normal metabolizers (e.g., CYP2C19*1/*1); however, dosage increases of 50-100% should be considered along with efficacy monitoring for treatment of H. pylori infection and erosive esophagitis due to an increased risk of therapeutic failure. In patients who are CYP2C19 ultrarapid metabolizers (e.g., CYP2C19*17/*17), consider increasing the starting dosage by 100% (may give in divided doses) and monitor for efficacy due to the risk of therapeutic failure.

Cautions for Omeprazole

Contraindications

• Known hypersensitivity reactions (including anaphylaxis) to omeprazole, esomeprazole, or other substituted benzimidazoles (e.g., lansoprazole, pantoprazole, rabeprazole), or any ingredient in the formulation.

• Concomitant use of proton-pump inhibitors (PPIs), including omeprazole, and rilpivirine is contraindicated.

Warnings/Precautions

Warnings and Precautions

Presence of Gastric Malignancy

Response to omeprazole in adults does not preclude presence of occult gastric neoplasm.

Consider additional follow-up and diagnostic testing in adults, and additionally, an endoscopy in older adults, with suboptimal response or early symptomatic relapse after treatment completion.

Acute Tubulointerstitial Nephritis

Acute tubulointerstitial nephritis (TIN) reported with proton-pump inhibitors (PPIs); can occur at any point during therapy. Clinical presentation may vary and can present as symptomatic hypersensitivity reactions to non-specific symptoms of decreased renal function such as malaise, nausea, or anorexia. Some cases diagnosed upon biopsy without any extra-renal manifestations (e.g., fever, rash, arthralgia).

Discontinue omeprazole and evaluate patient if acute TIN suspected.

Clostridioides difficile-associated Diarrhea

PPIs associated with possible increased risk of Clostridioides difficile-associated diarrhea, particularly in hospitalized patients.

Consider diagnosis of C. difficile-associated diarrhea for diarrhea that does not improve. Advise patients to contact their clinician if watery stools, abdominal pain , and persistent fever occur.

Use lowest effective dosage and shortest duration of therapy appropriate for patient's clinical condition.

Bone Fracture

Several observational studies suggest that use of PPIs, particularly in high dosages and/or for prolonged periods of time (i.e., ≥1 year), may be associated with increased risk of osteoporosis-related fractures of the hip, wrist, or spine.

Use lowest effective dosage and shortest duration of therapy appropriate for patient’s clinical condition. Patients at risk for osteoporosis-related fractures should be managed according to current treatment guidelines.

Severe Cutaneous Adverse Reactions

Reports of severe cutaneous adverse reactions (SCARS), including Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP), suggest association with PPIs.

Discontinue omeprazole at the first signs or symptoms of SCARS or hypersensitivity reactions and consider further evaluation.

Cutaneous and Systemic Lupus Erythematosus

New onset cases of cutaneous lupus erythematosus (CLE) and systemic lupus erythematosus (SLE) and exacerbations of existing disease reported.

Avoid administering PPI therapy for longer than appropriate for the clinical condition. If signs or symptoms of CLE or SLE occur, discontinue omeprazole and refer to appropriate specialist for evaluation. After discontinuation, majority of patients improve in 4−12 weeks, although serological testing (e.g., antinuclear antibodies) may remain positive and serological test elevations may not resolve until after clinical improvement is noted.

Interaction with Clopidogrel

Concurrent use of omeprazole with clopidogrel, which is metabolized to its active metabolite by CYP2C19, reduces pharmacologic activity of clopidogrel.

Avoid concomitant use. Consider an alternative antiplatelet agent.

Cyanocobalamin (Vitamin B12 Deficiency)

Cyanocobalamin deficiency reported rarely. Chronic daily administration of acid-suppressive therapy over long periods (e.g., ≥3 years) can cause malabsorption of cyanocobalamin.

Consider cyanocobalamin deficiency if clinical symptoms consistent with the diagnosis observed.

Hypomagnesemia and Mineral Metabolism

Long-term use (for ≥3 months; in most cases, ≥1 year) of PPIs may rarely be associated with increased risk of hypomagnesemia. Serious adverse events include tetany, arrhythmias, and seizures.

In patients expected to receive long-term PPI therapy or in those receiving a PPI concomitantly with digoxin or drugs that may cause hypomagnesemia (e.g., diuretics), consider monitoring serum magnesium concentrations prior to initiation of prescription PPI therapy and periodically thereafter.

Prior to initiating omeprazole, consider monitoring serum magnesium and calcium concentrations and periodic monitoring thereafter in patients at risk for hypocalcemia (e.g., hypoparathyroidism). Supplement magnesium and calcium as needed during omeprazole therapy.. Consider discontinuing PPI if hypocalcemia is refractory to treatment.

Interaction with St. John's Wort or Rifampin

Omeprazole concentrations can be substantially reduced by drugs that induce CYP2C19 or CYP3A4 (e.g., rifampin, St. John’s wort [Hypericum perforatum]).

Avoid concomitant use of omeprazole with St. John’s wort or rifampin.

Interaction with Diagnostic Investigations for Neuroendocrine Tumors

Increases in intragastric pH can cause increased serum chromogranin A (CgA) concentrations, which may result in false-positive results for diagnostic tests for neuroendocrine tumors.

Temporarily discontinue omeprazole therapy ≥14 days before assessing CgA concentrations and consider repeating the test if initial CgA concentrations are high. Use of the same commercial laboratory is recommended for testing as reference ranges between tests may vary.

Interaction with Methotrexate

Concomitant use of PPIs, including omeprazole, with methotrexate (primarily at high doses) may result in elevated and prolonged serum methotrexate and/or metabolite concentrations; can possibly result in methotrexate toxicity.

Temporary discontinuance of PPI therapy may be considered in some patients receiving high-dose methotrexate.

Fundic Gland Polyps

Long-term use (especially ≥1 year) of PPI therapy may be associated with increased risk of fundic gland polyps.

Administer PPIs for shortest duration appropriate for the clinical condition.

Considerations with Sodium Content

Each mL of reconstituted omeprazole and sodium bicarbonate powder kit for oral suspension (Konvomep) contains 84 mg of sodium bicarbonate (equivalent to 1 mEq/mL of sodium); total sodium content from inactive and active ingredients is 1.14 mEq/mL. Each 20-mL dose of Konvomep delivers 40 mg of omeprazole and 1680 mg of sodium bicarbonate (526 mg [22.8 mEq] of sodium). Each 20- or 40-mg conventional immediate-release capsule contains 1100 mg of sodium bicarbonate (304 mg [13 mEq] of sodium), and each 20- or 40-mg single- dose packet of powder for immediate-release oral suspension contains 1680 mg of sodium bicarbonate (460 mg [20 mEq] of sodium).

Consider sodium content in patients whose sodium intake must be restricted or in those at risk for congestive heart failure; increased sodium intake may cause edema and weight increase. Sodium bicarbonate may cause metabolic alkalosis, and chronic administration of sodium bicarbonate with calcium or milk may cause milk-alkali syndrome. Avoid omeprazole and sodium bicarbonate in patients with Bartter’s syndrome, hypokalemia, hypocalcemia, or acid-base abnormalities.

Specific Populations

Pregnancy

Adequate and controlled studies of omeprazole in pregnancy not available. Available epidemiologic data have not demonstrated increased risk of major congenital malformations or other adverse outcomes with first trimester exposure. Reproductive studies in animals demonstrated dose-dependent increases in embryolethality.

Manufacturers state several studies reported no adverse short-term effects in infants when a single oral or IV dose of omeprazole was administered to pregnant women as premedication for cesarean section under general anesthesia.

Available data on sodium bicarbonate administration during pregnancy have not identified a drug-associated risk of major fetal malformations or miscarriage.

Lactation

Limited data suggest distributed into human milk. Effects on milk production and on the breast-fed infant unknown.

Consider developmental and health benefits of breast-feeding along with mother’s clinical need for omeprazole and any potential adverse effects on the breast-fed infant from the drug or from underlying maternal condition.

Pediatric Use

Safety and efficacy of delayed-release oral suspension established for treatment of erosive esophagitis in pediatric patients ≥1 month of age. Safety and efficacy of delayed-release oral suspension established for treatment of symptomatic GERD and maintenance of healing of erosive esophagitis in pediatric patients 1−16 years of age.

Safety and efficacy of delayed-release capsules established for treatment of symptomatic GERD and maintenance of healing of erosive esophagitis in pediatric patients 2−16 years of age.

Safety and efficacy of omeprazole delayed-release oral suspension not established in pediatric patients <1 month of age or for other uses in pediatric patients.

Safety and efficacy of omeprazole delayed-release capsules not established in pediatric patients <1 year of age for treatment of symptomatic GERD or maintenance of healing of erosive esophagitis. Safety and efficacy of omeprazole delayed-release capsules not established for pediatric patients for treatment of active duodenal ulcer, H. pylori eradication to reduce the risk of duodenal ulcer recurrence, treatment of active benign gastric ulcer, or pathological hypersecretory conditions.

Safety and efficacy of immediate-release capsules or immediate-release oral suspension not established in pediatric patients.

Safety and efficacy of omeprazole and sodium bicarbonate powder kit for oral suspension (Konvomep) not established in pediatric patients.

Safety and efficacy of co-packaged omeprazole delayed-release capsules, clarithromycin tablets, and amoxicillin capsules (Omeclamox-Pak) not established in pediatric patients with Helicobacter pylori.

Respiratory adverse reactions and accidental injuries reported more frequently in pediatric patients 2−16 years of age than in adults.

Geriatric Use

No substantial differences in efficacy and safety relative to younger adults, but increased sensitivity cannot be ruled out.

Hepatic Impairment

Increased bioavailability in chronic liver disease (Child-Pugh Class A, B, and C), reflecting decreased first-pass effect and increase in elimination half-life.

Renal Impairment

In patients with chronic renal impairment (Clcr 10—62 mL/minute per 1.73 m²), disposition of omeprazole similar to that in normal renal function, although slight increase in bioavailability possible; this increase not considered clinically meaningful.

Pharmacogenomic Considerations

Most PPIs undergo metabolism by CYP2C19 into inactive metabolites. Systemic exposure to omeprazole varies by patient metabolism status (poor metabolizers > intermediate metabolizers > extensive metabolizers). Consult Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines for dosing recommendations based on metabolism status.

Common Adverse Effects

In adults (≥2%): Headache, abdominal pain, nausea, diarrhea, and flatulence.

Pediatric patients: Adverse effects generally similar to those reported in adults, except that respiratory system events and fever occurred more frequently.

Drug Interactions

In vivo, substrate and inhibitor of CYP2C19, and a substrate of CYP3A4. Also inhibits CYP2C19.

Drugs Metabolized by Hepatic Microsomal Enzymes

Interactions reported with drugs metabolized by CYP isoenzymes (e.g., cyclosporine, disulfiram); monitor and adjust dosage of these drugs if necessary.

Concomitant use with CYP2C19 substrates may affect exposure of CYP2C19 substrates.

Concomitant use with strong CYP2C19 or CYP3A4 inducers decreases exposure to omeprazole.

Concomitant use with CYP2C19 or CYP3A4 inhibitors increases exposure to omeprazole.

Monitor patients to determine if dosage adjustment or alternate therapy should be considered when such medications are used concomitantly with omeprazole.

Drugs that Cause Hypomagnesemia

Potential interaction in patients receiving diuretics (i.e., loop or thiazide diuretics) or other drugs that may cause hypomagnesemia. Consider monitoring magnesium concentrations prior to initiation of prescription proton-pump inhibitor therapy and periodically thereafter.

Gastric pH-dependent Drugs

Omeprazole-induced increases in gastric pH may affect bioavailability of gastric pH-dependent drugs such as itraconazole, ketoconazole, mycophenolate mofetil, nilotinib, dasatinib, iron salts, or erlotinib. Refer to prescribing information for other drugs that depend on gastric pH for absorption.

Antiretroviral Agents

Effects of PPIs on antiretroviral agents variable; clinical importance and mechanisms behind these interactions are not always known. See prescribing information for antiretroviral products (including those containing ritonavir) when used concomitantly with omeprazole.

Specific Drugs

Omeprazole Pharmacokinetics

Absorption

Bioavailability

Absolute bioavailability with 20–40 mg dose of delayed-release capsules is about 30–40%. Bioavailability increases slightly with repeated dosing.

Peak plasma concentrations and AUC are dose proportional up to doses of 40 mg; greater than linear response with doses above 40 mg.

Onset

Within 1 hour; maximum effect within 2 hours.

Duration

Duration of secretion inhibition is up to 72 hours; inhibition is 50% of maximum at 24 hours. Inhibition increases with repeated daily dosing, reaching steady-state plateau at 4 days. After discontinuance, gastric secretion gradually increases over 3–5 days.

Food

Administration of omeprazole and sodium bicarbonate-containing preparations 1 hour after meal decreases exposure compared to administration 1 hour before meal.

Special Populations

AUCs were lower in children 2—5 years of age than in children 6–16 years of age or in adults.

Geriatric patients: Bioavailability is increased.

In patients with chronic hepatic disease, bioavailability is increased to 100% due to decreased first-pass effect.

In Asian patients, AUCs increased 4-fold after a 20-mg dose.

Distribution

Extent

Limited data suggest may distribute into human milk.

Plasma Protein Binding

Approximately 95%.

Elimination

Metabolism

Undergoes first-pass metabolism.

Metabolized to inactive metabolites in the liver by CYP isoenzymes, principally CYP2C19, and to a lesser extent by CYP3A4.

Elimination Route

Excreted principally in urine (77%) as metabolites and to a lesser extent in feces.

Half-life

Delayed-release omeprazole preparations: 0.5–1 hour.

Omeprazole and sodium bicarbonate-containing preparations: Approximately 1 hour.

Special Populations

Geriatric patients: Elimination rate is somewhat decreased and plasma half-life is increased.

In patients with chronic hepatic disease, clearance is decreased, and plasma half-life is increased to almost 3 hours.

Stability

Storage

Oral

Delayed-release Capsules

Tight containers or original cartons at 20–25°C; protect from light and moisture.

Immediate-release Capsules

Tight, light-resistant containers at 20−25°C (may be exposed to 15–30°C); protect from moisture.

Powder for Delayed-release or Immediate-release Suspension

Single-dose packets: 25°C (may be exposed to 15–30°C). Protect from light and moisture.

Powder and Kit for Suspension

2–8°C; protect from light; do not freeze.

Store reconstituted suspension at 2–8°C for up to 30 days; discard remaining suspension after 30 days.

Actions

• Substituted benzimidazole gastric antisecretory agent.

• Inhibits basal and stimulated gastric acid secretion.

• Prolonged binding to surface of parietal cell secretory enzymes; binds to the hydrogen-potassium ATPase (proton- or acid pump), blocking the final step in acid secretion.

• Combined therapy with omeprazole and 1 or more appropriate anti-infectives (e.g., amoxicillin, clarithromycin) can effectively eradicate Helicobacter pylori gastric infection.

Advice to Patients

• Inform patients to read the patient information (including the Medication Guide and Instructions for Use, if available) before beginning omeprazole therapy.

• Inform patients of the importance of swallowing omeprazole delayed-release capsules intact, without crushing or chewing. Advise patients of the importance of taking delayed-release capsules before meals.

• If mixed with applesauce, inform patients of the importance of mixing omeprazole delayed-release capsule contents with applesauce soft enough to swallow without chewing. Advise patients on the importance of not using hot applesauce. Inform patients of the importance of immediately swallowing mixture with a glass of cool water, without crushing or chewing; inform patients of the importance of not storing for later use.

• Inform patients of the importance of swallowing immediate-release omeprazole capsules intact with water and not with other fluid. Inform patients of the importance of not opening the capsule or mixing the contents with food.

• Inform patients of the importance of taking sodium bicarbonate-containing preparations at least 1 hour before a meal.

• Inform patients of the importance of not substituting two 20-mg immediate-release capsules of omeprazole for one 40-mg capsule, or two 20-mg powder for immediate-release oral suspension packets for one 40-mg packet.

• Inform patients of the importance of mixing powder for oral suspension in small cup with water, not with other fluids or food. Inform patients of the importance of swallowing suspension immediately, then refilling cup with water and swallowing to ensure complete ingestion of dose.

• Inform patients of the importance of reconstituting omeprazole and sodium bicarbonate powder kit for oral suspension (Konvomep) prior to administration and storing the reconstituted suspension in the refrigerator. Advise patients to discard the reconstituted suspension after 30 days.

• If a dose is missed, advise patients to take the dose as soon as possible; if the next scheduled dose is due, advise patients not to take the missed dose and to take the next dose on time. Advise patients not to take two doses at one time to make up for a missed dose.

• Inform patients of the importance of taking Omeclamox-Pak twice daily in the morning and evening before a meal. Inform patients that each dose consists of 4 pills that must not be crushed or chewed, and that each pill should be swallowed whole.

• Advise patients and caregivers to contact their clinician immediately if the patient experiences signs or symptoms of acute tubulointerstitial nephritis.

• Advise patients on a sodium-restricted diet or patients at risk of developing congestive heart failure of the sodium content of bicarbonate-containing omeprazole preparations.

• Advise patients to immediately contact their clinician if they have prolonged diarrhea that does not improve.

• Advise patients that use of multiple daily doses of omeprazole for an extended period of time may increase the risk of osteoporosis-related fractures of the hip, wrist, or spine and to report any fractures to their clinician.

• Advise patients to discontinue omeprazole immediately and contact their clinician if any new or worsening signs or symptoms of a severe cutaneous adverse reaction or hypersensitivity occur.

• Advise patients to discontinue omeprazole and to contact their clinician for any new or worsening symptoms associated with cutaneous or systemic lupus erythematosus.

• Advise patients to report to their clinician any symptoms that may be associated with vitamin B₁₂ deficiency if they have been receiving omeprazole for longer than 3 years.

• Inform patients that antacids may be used concomitantly with omeprazole delayed-release capsules or oral suspension as needed for pain relief.

• Advise patients or caregivers to report to their clinician any symptoms that may be associated with hypomagnesemia, hypocalcemia, and/or hypokalemia if they have been receiving omeprazole for at least 3 months.

• Advise patients of the importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs and dietary or herbal supplements, as well as any concomitant illnesses. Advise patients to inform their clinician if they start treatment with clopidogrel, St. John's wort, or rifampin, or if they take high-dose methotrexate.

• Advise women of the importance of informing clinicians if they are or plan to become pregnant or plan to breast-feed.

• Inform patients of other important precautionary information.

Additional Information

The American Society of Health-System Pharmacists, Inc. represents that the information provided in the accompanying monograph was formulated with a reasonable standard of care, and in conformity with professional standards in the field. Readers are advised that decisions regarding use of drugs are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and that the information contained in the monograph is provided for informational purposes only. The manufacturer’s labeling should be consulted for more detailed information. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information contained in the monograph is not a substitute for medical care.

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

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Frequently asked questions

• Pantoprazole vs. omeprazole: What's the difference between them?
• What foods should I avoid when taking omeprazole?
• Can you take an antacid with omeprazole?
• Is famotidine safer than omeprazole for heartburn?
• Can I take omeprazole in the morning and famotidine at night?
• Is omeprazole (Prilosec) bad for your kidneys?
• Does omeprazole cause cancer?
• How soon after taking levothyroxine can I take omeprazole?
• When's the best time to take omeprazole: before or after a meal?

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