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Omeprazole (Monograph)

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

Patient Monitoring

Dispensing and Administration Precautions

Other General Considerations

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.

Table 1. Oral Omeprazole Dosage for Treatment of Symptomatic GERD in Pediatric Patients 1–16 Years of Age352

Body Weight (kg)

Omeprazole Dosage

≥5 to <10

5 mg once daily

≥10 to <20

10 mg once daily

≥20

20 mg once daily

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.

Table 2. Oral Omeprazole Dosage for Treatment of GERD in Pediatric Patients 2–16 Years of Age1

Body Weight (kg)

Omeprazole Dosage

≥10 to <20

10 mg once daily

≥20

20 mg once daily

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.

Table 3. Oral Omeprazole Dosage for Treatment of Erosive Esophagitis in Pediatric Patients 1 Month to <1 Year of Age352

Body Weight (kg)

Omeprazole Dosage

≥3 to <5

2.5 mg once daily

≥5 to <10

5 mg once daily

≥10

10 mg once daily

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.

Table 4. Oral Omeprazole Dosage for Treatment of Erosive Esophagitis in Pediatric Patients 1–16 Years of Age352

Body Weight (kg)

Omeprazole Dosage

≥5 to <10

5 mg once daily

≥10 to <20

10 mg once daily

≥20

20 mg once daily

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.

Table 5. Oral Omeprazole Dosage for Maintenance Therapy (Maintenance of Healing) in Pediatric Patients 1–16 Years of Age352

Body Weight (kg)

Omeprazole Dosage

≥5 to <10

5 mg once daily

≥10 to <20

10 mg once daily

≥20

20 mg once daily

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.

Table 6. Oral Omeprazole Dosage for Treatment of Erosive Esophagitis in Pediatric Patients 2–16 Years of Age1

Body Weight (kg)

Omeprazole Dosage

≥10 to <20

10 mg once daily

≥20

20 mg once daily

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.

Table 7. Oral Omeprazole Dosage for Maintenance Therapy (Maintenance of Healing) in Pediatric Patients 2–16 Years of Age1

Body Weight (kg)

Omeprazole Dosage

≥10 to <20

10 mg once daily

≥20

20 mg once daily

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 (Clcr 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

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

Drug or Test

Interaction

Comments

Atazanavir

Decreased atazanavir exposure; possible loss of virologic response and development of drug resistance

Avoid concomitant use of atazanavir and omeprazole

Other antiretroviral agents available that do not have clinically important interactions with omeprazole

Cilostazol

Increased plasma concentrations and AUC of cilostazol and 3,4-dihyro-cilostazol

When used concomitantly, reduction of cilostazol dosage from 100 mg twice daily to 50 mg twice daily recommended

Citalopram

Increased citalopram exposure and increased risk of QT prolongation

When used concomitantly, limit citalopram dosage to 20 mg daily

Clarithromycin

Increased plasma concentrations and AUC of omeprazole, clarithromycin, and 14-hydroxyclarithromycin

Clopidogrel

Reduced plasma concentrations of clopidogrel’s active metabolite; possible reduction of therapeutic efficacy

Avoid concomitant use of omeprazole with clopidogrel

Consider use of alternative antiplatelet agent

Cyclosporine

Potential for altered cyclosporine metabolism

Monitor patients and consider dosage adjustment of cyclosporine if needed

Diazepam

Potential increased diazepam exposure

When used concomitantly, monitor patients for increased sedation and reduce diazepam dosage as needed

Digoxin

Possible increased digoxin exposure because of increased digoxin bioavailability

Possible increased risk of hypomagnesemia

When used concomitantly, monitor serum digoxin concentrations and adjust digoxin dosage as needed to maintain therapeutic concentrations

For patients on prolonged proton-pump inhibitor (PPI) therapy or receiving a PPI with digoxin, consider monitoring magnesium concentrations prior to initiating PPI therapy and periodically thereafter

Disulfiram

Potential for altered disulfiram metabolism

Monitor patients and consider dosage adjustment of disulfiram if needed

Diuretics (i.e., loop or thiazide diuretics)

Possible increased risk of hypomagnesemia

Consider monitoring magnesium concentrations prior to initiation of prescription PPI therapy and periodically thereafter

Methotrexate

Possible prolonged and elevated serum concentrations of methotrexate and/or its metabolite hydroxymethotrexate; possible methotrexate toxicity

Reported primarily with high methotrexate dosages

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

Mycophenolate mofetil

Omeprazole may reduce mycophenolate mofetil absorption

Reduced exposure to active metabolite of mycophenolate mofetil (mycophenolic acid) reported; clinical importance on transplant rejection not established

Use omeprazole with caution in transplant recipients receiving mycophenolate mofetil

Nelfinavir

Decreased nelfinavir plasma concentrations; possible loss of virologic response and development of drug resistance

Concomitant use of nelfinavir and omeprazole not recommended

Other antiretroviral agents available that do not have clinically important interactions with omeprazole

Phenytoin

Potential for increased phenytoin exposure

If phenytoin and omeprazole used concomitantly, monitoring of phenytoin serum concentrations is recommended

Dosage adjustment of phenytoin may be necessary in order to maintain therapeutic concentrations

Rifampin

Potential for decreased omeprazole concentrations

Avoid concomitant use

Rilpivirine

Decreased rilpivirine plasma concentrations; possible loss of virologic response and development of drug resistance

Concomitant use of rilpivirine with PPIs, including omeprazole, is contraindicated

Secretin stimulation test

Potential for overresponsive gastric secretion during testing, which may falsely suggest gastrinoma

Temporarily discontinue omeprazole ≥14 days before secretin stimulation testing to allow gastrin levels to return to baseline

St. John’s wort (Hypericum perforatum)

Decreased omeprazole concentrations

Avoid concomitant use

Tacrolimus

Potential for increased serum tacrolimus concentrations, particularly in intermediate or poor metabolizers of CYP2C19

If used concomitantly, monitoring of serum tacrolimus concentrations is recommended

Dosage adjustment of tacrolimus may be required to maintain therapeutic tacrolimus concentrations

Tests for neuroendocrine tumors

Increased serum chromogranin A (CgA) concentrations (secondary to omeprazole-induced increase in intragastric pH) may produce false-positive results

Temporarily discontinue omeprazole ≥14 days before assessing CgA concentrations; consider repeating test if initial CgA concentrations are elevated

Use of same commercial laboratory recommended for serial testing due to variances in reference ranges

Urine tests for tetrahydrocannabinol (THC)

False-positive urine screening tests for THC reported

Confirm positive urine test results using an alternative testing method

Voriconazole

Increased peak plasma concentrations and AUC of omeprazole

Dosage adjustment of omeprazole usually not required, but may be considered in patients receiving high dosages of omeprazole (e.g., patients with Zollinger-Ellison syndrome)

Warfarin

Increased INR and prothrombin time

Because increases in INR and prothrombin time can lead to abnormal bleeding and death, monitoring of INR and prothrombin time and adjustment of warfarin dosage may be necessary

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

Advice to Patients

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

Omeprazole

Routes

Dosage Forms

Strengths

Brand Names

Manufacturer

Oral

Capsules, delayed-release (containing enteric-coated granules)

10 mg*

Omeprazole capsules, delayed-release

20 mg*

Omeprazole capsules, delayed-release

40 mg*

Omeprazole capsules, delayed-release

Omeprazole Magnesium

Routes

Dosage Forms

Strengths

Brand Names

Manufacturer

Oral

For suspension, delayed-release (containing enteric-coated granules)

2.5 mg (of omeprazole) per packet

PriLOSEC

AstraZeneca

10 mg (of omeprazole) per packet

PriLOSEC

AstraZeneca

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

Omeprazole and Sodium Bicarbonate

Routes

Dosage Forms

Strengths

Brand Names

Manufacturer

Oral

For suspension, powder kit

Bottle of 0.18 grams omeprazole powder and bottle of diluent containing sodium bicarbonate 7.56 grams per 90 mL

Konvomep (2 mg omeprazole and 84 mg sodium bicarbonate per mL [after reconstitution])

Azurity Pharmaceuticals

Bottle of 0.3 grams omeprazole powder and bottle of diluent containing sodium bicarbonate 12.6 grams per 150 mL

Konvomep (2 mg omeprazole and 84 mg sodium bicarbonate per mL [after reconstitution])

Azurity Pharmaceuticals

Bottle of 0.6 grams omeprazole powder and bottle of diluent containing sodium bicarbonate 25.2 grams per 300 mL

Konvomep (2 mg omeprazole and 84 mg sodium bicarbonate per mL [after reconstitution])

Capsules, immediate-release

20 mg omeprazole and 1100 mg sodium bicarbonate*

Omeprazole capsules, immediate-release

40 mg omeprazole and 1100 mg sodium bicarbonate*

Omeprazole capsules, immediate-release

For suspension, immediate-release powder

20 mg of omeprazole and 1680 mg of sodium bicarbonate per packet*

Omeprazole suspension, immediate-release powder

40 mg of omeprazole and 1680 mg of sodium bicarbonate per packet*

Omeprazole suspension, immediate-release powder

Omeprazole Combinations

Routes

Dosage Forms

Strengths

Brand Names

Manufacturer

Oral

Various

20 mg omeprazole, 500 mg clarithromycin, 500 mg amoxicillin

Omeclamox-Pak (Pack of 10 daily administration cards for morning and evening; each containing two omeprazole delayed-release capsules, two clarithromycin tablets, and four amoxicillin capsules)

10 mg omeprazole, amoxicillin 250 mg, rifabutin 12.5 mg

Talicia

AHFS DI Essentials™. © Copyright 2025, Selected Revisions May 10, 2025. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.

† Off-label: Use is not currently included in the labeling approved by the US Food and Drug Administration.

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Frequently asked questions

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