Brand names: PriLOSEC, Zegerid
Drug class: Proton-pump Inhibitors
- Antiulcer Agents
- Gastric Antisecretory Agents
- Acid-pump Inhibitors
VA class: GA900
Chemical name: 5-Methoxy-2-[[(4-methoxy-3,5-dimethyl-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole
Molecular formula: C₁₇H₁₉N₃O₃SC₃₄H₃₆MgN₆O₆S₂
CAS number: 73590-58-6

Medically reviewed by Drugs.com on Feb 6, 2023. Written by ASHP.

Introduction

Acid- or proton-pump inhibitor; gastric antisecretory agent.

Uses for Omeprazole

Gastroesophageal Reflux (GERD)

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

Short-term treatment of erosive esophagitis (endoscopically diagnosed) in patients with GERD.

Maintain healing and decrease recurrence of erosive esophagitis.

Short-term self-medication for symptomatic relief of frequent (e.g., 2 or more days a week) heartburn in adults ≥18 years of age.

Duodenal Ulcer

Short-term treatment of active duodenal ulcer (endoscopically or radiographically confirmed).

Treatment of Helicobacter pylori infection and duodenal ulcer disease. Used in conjunction with amoxicillin and clarithromycin (triple therapy) or clarithromycin (dual therapy); has been used in other multidrug regimens^{† [off-label]}.

Gastric Ulcer

Short-term treatment and symptomatic relief of active benign gastric ulcer.

Crohn’s Disease-associated Ulcers

Some evidence for use of proton-pump inhibitors (e.g., omeprazole) for gastric acid suppressive therapy as an adjunct in the management of upper GI Crohn’s disease^{† [off-label]}, including esophageal, gastroduodenal, and jejunoileal disease.

Pathologic GI Hypersecretory Conditions

Long-term treatment of Zollinger-Ellison syndrome, multiple endocrine adenomas, or systemic mastocytosis in adults.

Upper GI Bleeding

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

Omeprazole Dosage and Administration

Administration

Omeprazole is acid-labile. To avoid decomposition in acidic pH of the stomach, delayed-release capsules and delayed-release oral suspension (Prilosec) contain enteric-coated granules of the drug; immediate-release capsules and immediate-release oral suspension (Zegerid) contain sodium bicarbonate to protect the drug.

Oral Administration

Immediate-release Capsules

Swallow intact with a glass of water at least 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 glass of cool water to ensure complete swallowing. Applesauce should not be hot and should be soft enough to swallow without chewing.

Delayed-release Tablets

Tablets for self-medication: swallow intact with a glass of water before breakfast; do not chew, crush, or crush in food.

Powder for Immediate-release Oral Suspension

Administer at least 1 hour prior to a meal.

May use antacids, antacid/alginic acid combinations, histamine H₂-receptor antagonists, or histamine H₂-receptor antagonist and antacid combinations for “breakthrough” symptoms, but efficacy of these preparations has not been established.

Empty 20- or 40-mg single-dose packet for oral suspension into small cup containing 15–30 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.

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.

Dosage

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

Pediatric Patients

Gastroesophageal Reflux

GERD.

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

Administered for 4 weeks in one study.

Treatment of Erosive Esophagitis.

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

On a mg/kg basis, dosage of omeprazole required to heal erosive esophagitis is greater in children than that required in adults. In an uncontrolled open-label study, dosages required for healing were 0.7–3.5 mg/kg daily (maximum 80 mg daily) for 3–6 months; about 90% of children healed in the first 3 months, and about 5% required a second course of treatment. Dosage of 0.7 mg/kg daily resulted in healing in 44% of children; an additional 28% of the children studied required a dosage of 1.4 mg/kg daily for healing to occur.

Maintenance of Healing of Erosive Esophagitis.

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

Maintenance therapy continued 2 years in one study. In an uncontrolled open-label study, maintenance dosages were half the dosages required for initial healing in 54% of children, while 46% required dosage increase (0.7–2.8 mg/kg daily) for all or part of the study.

Adults

GERD

GERD without Erosive Esophagitis

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

20 mg once daily for up to 4 weeks.

Treatment of Erosive Esophagitis

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

20 mg once daily until healing occurs (usually within 4–8 weeks); 40 mg once daily may be required. 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.

Maintenance of Healing of Erosive Esophagitis

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

20 mg once daily. Chronic, lifelong therapy may be appropriate.

Self-medication for Frequent Heartburn

Oral (Delayed-release Tablets)

20 mg daily in the morning for 14 days. Do not exceed recommended dosage or duration; do not administer more than one course every 4 months. May relieve symptoms within 24 hours, but 1–4 days may be required for complete relief.

Duodenal Ulcer

Treatment of Active Duodenal Ulcer

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

20 mg once daily until healing occurs (usually within 2–4 weeks); an additional 4 weeks with therapy may be beneficial. Patients who responded poorly to histamine H₂-receptor antagonists may require up to 40 mg daily.

Treatment of Helicobacter pylori Infection and Duodenal Ulcer

Oral (Delayed-release Capsules or Oral Suspension)

Triple therapy: 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: 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.

Gastric Ulcer

Treatment

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

40 mg once daily for 4–8 weeks.

Pathologic GI Hypersecretory Conditions

Zollinger-Ellison Syndrome

Oral (Delayed-release Capsules or Delayed-release Oral 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. May require dosages of up to 360 mg daily (given in 3 divided doses).

Multiple Endocrine Adenomas

Oral (Delayed-release Capsules or Delayed-release Oral 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. May require dosages of up to 360 mg daily (given in 3 divided doses).

Systemic Mastocytosis

Oral (Delayed-release Capsules or Delayed-release Oral 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. May require dosages of up to 360 mg daily (given in 3 divided doses).

Upper GI Bleeding

Reduction of Risk of Upper GI Bleeding in Critically Ill Adults

Oral (Immediate-release Oral Suspension)

Initially, 40 mg followed by 40 mg after 6–8 hours on the first day, then 40 mg once daily for up to 14 days. Safety and efficacy for >14 days not established.

Special Populations

Hepatic Impairment

Consider dosage reduction, particularly in patients receiving long-term therapy for maintenance of healing of erosive esophagitis.

Renal Impairment

No dosage adjustment necessary.

Asians

Consider dosage reduction, especially in patients receiving long-term therapy for maintenance of healing of erosive esophagitis.

Cautions for Omeprazole

Contraindications

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

Warnings/Precautions

Sensitivity Reactions

Hypersensitivity Reactions

Hypersensitivity reactions (e.g., anaphylaxis, angioedema, bronchospasm, interstitial nephritis, urticaria) reported.

Warnings/Precautions

Gastric Malignancy

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

Atrophic Gastritis

Atrophic gastritis reported occasionally with long-term use.

Clostridium difficile Infection

Proton-pump inhibitors associated with possible increased (1.4–2.75 times) risk of Clostridium difficile infection, including C. difficile-associated diarrhea and colitis (CDAD; also known as antibiotic-associated diarrhea and colitis or pseudomembranous colitis). Many patients also had other risk factors for CDAD. May be severe; colectomy and, rarely, death reported.

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

Consider CDAD if persistent diarrhea develops and manage accordingly; initiate supportive therapy (e.g., fluid and electrolyte management), anti-infective therapy directed against C. difficile (e.g., metronidazole, vancomycin), and surgical evaluation as clinically indicated.

Sodium Bicarbonate

Each 20- and 40- mg conventional immediate-release capsule contains 1100 mg of sodium bicarbonate (304 mg [13 mEq] of sodium), and each 20- and 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 when used in patients requiring restricted salt intake.

Caution in patients with Bartter’s syndrome, hypokalemia, respiratory alkalosis, and acid-base abnormalities. Long-term administration of sodium bicarbonate with calcium or milk may cause milk-alkali syndrome. Long-term use of sodium bicarbonate may lead to systemic alkalosis, and increased sodium intake can produce edema and weight increase. Sodium bicarbonate is contraindicated in patients with metabolic alkalosis or hypocalcemia.

Respiratory Effects

Administration of proton-pump inhibitors has been associated with an increased risk for developing certain infections (e.g., community-acquired pneumonia).

Bone Fracture

Several observational studies suggest that use of proton-pump inhibitors, particularly in high dosages (i.e., multiple daily doses) 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. Magnitude of risk is unclear; causality not established. FDA is continuing to evaluate this safety concern.

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

Individuals at risk for osteoporosis-related fractures should receive an adequate intake of calcium and vitamin D; assess and manage these patients’ bone health according to current standards of care.

Hypomagnesemia

In patients expected to receive long-term proton-pump inhibitor therapy or in patients currently receiving digoxin or drugs that may cause hypomagnesemia (e.g., diuretics), consider measuring serum magnesium concentrations prior to initiation of prescription proton-pump inhibitor therapy and periodically thereafter.

Hypomagnesemia, symptomatic and asymptomatic, reported rarely in patients receiving long-term therapy (≥3 months or, in most cases, >1 year) with proton-pump inhibitors, including omeprazole. Serious adverse effects include tetany, seizures, tremors, carpopedal spasm, arrhythmias (e.g., atrial fibrillation, supraventricular tachycardia), and abnormal QT interval. Paresthesia, muscle weakness, muscle cramps, lethargy, fatigue, and unsteadiness may occur. Most patients required magnesium replacement and discontinuance of the proton-pump inhibitor. Hypomagnesemia resolved within 1 week (median) following discontinuance and recurred within 2 weeks (median) of rechallenge.

Cardiovascular Effects

Preliminary safety data from 2 long-term clinical trials comparing esomeprazole or omeprazole with antireflux surgery in patients with severe GERD raised concerns about a potential increased risk of cardiac events (e.g., MI, heart failure, sudden death) in patients receiving these drugs. After reviewing data from these and other studies, FDA has concluded that long-term use of these drugs is not likely to be associated with an increased risk of such cardiac events. FDA recommends that clinicians continue to prescribe and patients continue to use these drugs in the manner described in the manufacturers’ labelings.

Specific Populations

Pregnancy

Category C.

Lactation

Distributed into milk. Discontinue nursing or the drug.

Pediatric Use

Safety and efficacy of delayed-release capsules or delayed-release oral suspension established for treatment of symptomatic GERD, treatment of erosive esophagitis, and maintenance of healing of erosive esophagitis in pediatric patients 1–16 years of age. Safety and efficacy not established in infants <1 year of age or for other uses in pediatric patients.

Safety and efficacy for self-medication of frequent heartburn not established in children <18 years of age.

Safety and efficacy of immediate-release capsules or immediate-release oral suspension not established in pediatric patients <18 years of age.

Geriatric Use

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

Hepatic Impairment

Increased bioavailability and decreased clearance. Monitor patients receiving >20 mg daily for possible adverse effects. (See Hepatic Impairment under Dosage and Administration.)

Common Adverse Effects

In adults, diarrhea, nausea, constipation, abdominal pain, vomiting, headache, flatulence.

In pediatric patients, respiratory effects, fever (in children 1–2 years of age), accidental injuries (in children 2–16 years of age); otherwise, adverse effects generally similar to those in adults.

Interactions for Omeprazole

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

Drugs Metabolized by Hepatic Microsomal Enzymes

Potential to prolong elimination of drugs metabolized by oxidation in the liver. Interaction reported with drugs metabolized by CYP isoenzymes; monitor and adjust dosage of these drugs if necessary.

Drugs that Cause Hypomagnesemia

Potential pharmacologic interaction (possible increased risk of hypomagnesemia). Consider monitoring magnesium concentrations prior to initiation of prescription proton-pump inhibitor therapy and periodically thereafter. (See Hypomagnesemia under Cautions.)

Specific Drugs

Omeprazole Pharmacokinetics

Absorption

Bioavailability

Absolute bioavailability with 20–40 mg dose is about 30–40%. Bioavailability increases slightly with repeated dosing.

Following administration of delayed-release oral suspension, peak concentration and AUC are 88 and 87%, respectively, of values achieved after oral administration of delayed-release capsules.

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

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

Rate of absorption is decreased with meals. Most effective given about 30 minutes before a meal; bioavailability may be unaffected if given up to 2 minutes before a meal.

Administration of immediate-release oral suspension 1 hour after a meal decreases peak plasma concentrations (by 62%) and AUCs (by 26%).

Special Populations

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

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

Distribution

Extent

Omeprazole crosses the placenta and is distributed into milk.

Prolonged binding to gastric parietal proton pump enzyme.

Plasma Protein Binding

95%.

Elimination

Metabolism

Undergoes first-pass metabolism. Metabolized to inactive metabolites in the liver by CYP isoenzymes, principally CYP2C19, and to lesser extent by CYP3A4.

Elimination Route

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

Half-life

0.5–1 hour.

Special Populations

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, light-resistant containers at 15–30°C.

Immediate-release Capsules

25°C (may be exposed to 15–30°C).

Powder for Delayed-release or Immediate-release Suspension

Single-dose packets: 25°C (may be exposed to 15–30°C).

Tablets for Self-medication

Tight containers at 20–25°C; protect from high heat, humidity, and moisture.

Actions

• Inhibits basal and stimulated gastric acid secretion.

• Concentrates in acid conditions of parietal cell secretory canaliculi; forms active sulfenamide metabolite that irreversibly binds to and inactivates hydrogen-potassium ATPase (proton- or acid pump), blocking final step in secretion of hydrochloric acid. Acid secretion inhibited until additional hydrogen-potassium ATPase is synthesized, resulting in prolonged duration of action.

• Suppresses H. pylori in patients with duodenal ulcer and/or reflux esophagitis infected with the organism. Combined therapy with omeprazole and 1 or more appropriate anti-infectives (e.g., amoxicillin, clarithromycin) can effectively eradicate H. pylori gastric infection.

Advice to Patients

• Importance of swallowing delayed-release capsule intact, without crushing or chewing. Importance of taking delayed-release capsule at least 1 hour before a meal.

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

• Importance of swallowing immediate-release capsule intact with water and not with other fluid. Importance of not opening capsule or mixing the contents with food.

• Importance of taking immediate-release capsule and oral suspension at least 1 hour before a meal.

• Importance of not substituting two 20-mg immediate-release capsules for one 40-mg capsule or two 20-mg powder for immediate-release oral suspension packets for one 40-mg packet.

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

• Possible increased risk of Clostridium difficile infection; importance of contacting a clinician if persistent watery stools, abdominal pain, and fever occur.

• Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs. Antacids may be used concomitantly with delayed-release capsules or oral suspension as needed for pain relief. Antacids, antacids/alginic acid combinations, histamine H₂-receptor antagonists, or histamine H₂-receptor antagonist and antacid combinations may be used in conjunction with immediate-release oral suspension for “breakthrough” symptoms.

• Importance of advising patients that use of multiple daily doses of the drug for an extended period of time may increase the risk of fractures of the hip, wrist, or spine.

• Risk of hypomagnesemia; importance of immediately reporting and seeking care for any cardiovascular or neurologic manifestations (e.g., palpitations, dizziness, seizures, tetany).

• Importance of women informing their clinicians if they are or plan to become pregnant or plan to breast-feed.

• Importance of following dosage instructions when omeprazole magnesium is administered for self-medication. Advise patients that they should use the drug for self-medication only as directed for no longer than 14 days of continuous use and that they should not exceed one course of therapy every 4 months.

• Importance of discontinuing use as self-medication and consulting a clinician if heartburn persists or worsens, use of the drug for >14 days is needed, or >1 course of therapy is required every 4 months.

• Self-medication with omeprazole magnesium is not intended for immediate relief of heartburn; may relieve symptoms within 24 hours, but 1–4 days may be required for complete relief. Not intended to treat occasional (e.g., occurring once weekly or less) symptoms or to prevent occasional meal- or beverage-induced heartburn.

• Advise patients to consult their clinician before using omeprazole magnesium for self-medication if they have had heartburn for >3 months or are experiencing heartburn with lightheadedness, dizziness, or sweating; chest or shoulder pain with shortness of breath, sweating, lightheadedness, or pain spreading to the arms, neck, or shoulders; frequent chest pain; frequent wheezing (especially with heartburn); unexplained weight loss; nausea or vomiting; or stomach pain.

• Advise patients not to use omeprazole magnesium for self-medication and to consult a clinician if they have difficulty or pain with swallowing, are vomiting blood, or have bloody or blackened stools.

• Importance of informing patients of other important precautionary information. (See Cautions.)

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

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