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Omeprazole

Pronunciation

Pronunciation: oh-MEP-ra-zole
Class: Proton pump inhibitor

Trade Names

Prilosec
- Capsules, delayed-release, oral 10 mg
- Capsules, delayed-release, oral 20 mg
- Capsules, delayed-release, oral 40 mg

Prilosec
- Suspension, delayed-release, oral 2.5 mg
- Suspension, delayed-release, oral 10 mg

Prilosec OTC
- Tablets, delayed-release, oral 20 mg

Apo-Omeprazole (Canada)
Losec (Canada)
Losec MUPS (Canada)

Pharmacology

Suppresses gastric acid secretion by blocking acid (proton) pump within gastric parietal cell.

Slideshow: OTC Medication Use In Pregnancy: Wise or Worrisome?

Pharmacokinetics

Absorption

Absorption is rapid. T max is 0.5 to 3.5 h. Bioavailability of the capsules is 30% to 40% and increases upon repeat administration. The 40 mg capsules were bioequivalent when administered with or without applesauce; mean reduction in C max of 25% without a significant change in AUC occurred when the 20 mg capsules were administered with applesauce.

Distribution

95% protein bound.

Metabolism

Extensive in the liver by the CYP enzyme system.

Elimination

Little is unchanged drug in the urine. Approximately 77% is eliminated as 6 metabolites; the remainder is eliminated in the feces. The half-life is 0.5 to 1 h. Total body Cl is 500 to 600 mL/min.

Duration

Up to 72 h.

Special Populations

Renal Function Impairment

There is slight increase in bioavailability in patients with chronic renal impairment. No dose adjustment necessary.

Hepatic Function Impairment

In patients with chronic hepatic disease, bioavailability is increased, plasma half-life is increased to 3 h, and plasma Cl is decreased. Consider dose adjustment.

Elderly

The elimination rate is decreased. Bioavailability is increased. No dosage adjustment is necessary.

Children

Children 2 to 5 y of age have lower AUCs than children 6 to 16 y of age and adults.

Race

AUC is increased approximately 4-fold in Asian patients. Consider dose adjustment.

Indications and Usage

Short-term treatment of active duodenal ulcer; in combination with clarithromycin and amoxicillin to eradicate Helicobacter pylori ; in combination with clarithromycin to eradicate H. pylori ; short-term treatment of active benign gastric ulcer; treatment of heartburn and other symptoms associated with gastroesophageal reflux disease (GERD); short-term treatment of erosive esophagitis that has been diagnosed by endoscopy; maintenance of healing of erosive esophagitis; long-term treatment of pathological hypersecretory conditions (eg, Zollinger-Ellison syndrome, multiple endocrine adenomas, systemic mastocytosis).

Nonprescription

Treatment of frequent heartburn that occurs 2 or more times per week.

Unlabeled Uses

As alternate-day therapy in maintaining ulcer or GERD remission rates during long-term treatment after healing during a short course of therapy; treatment of GERD-related laryngitis symptoms in patients who have not responded to antireflux measures alone; treatment of GERD in infants and children; in combination with antibiotics (eg, amoxicillin, clarithromycin) for eradication of H. pylori in children; to improve enzyme absorption in cystic fibrosis patients with intestinal malabsorption.

Contraindications

Hypersensitivity to substituted benzimidazoles or to any component of the formulation.

Dosage and Administration

Active Duodenal Ulcer
Adults

PO 20 mg/day for 4 to 8 wk.

Gastric Ulcer
Adults

PO 40 mg once daily for 4 to 8 wk.

GERD and Maintenance of Healing of Erosive Esophagitis
Children 1 y of age and older

PO Weighing 5 to less than 10 kg, the dosage is 5 mg daily.

Weighing 10 kg to less than 20 kg, the dosage is 10 mg daily.

Weighing 20 kg or more, the dosage is 20 mg daily.

GERD With Erosive Esophagitis
Adults

PO 20 mg/day for 4 to 8 wk. For maintenance treatment, give 20 mg/day.

GERD Without Esophageal Lesions
Adults

PO 20 mg daily for up to 4 wk.

Heartburn (OTC)
Adults

PO 20 mg daily for 14 days. The 14-day course may be repeated every 4 mo.

H. pylori
Adults (triple therapy)

PO Omeprazole 20 mg plus clarithromycin 500 mg plus amoxicillin 1,000 mg each given 2 times daily for 10 days; continue omeprazole 20 mg/day for an additional 18 days if an ulcer is present at start of therapy.

Adults (dual therapy)

PO Omeprazole 40 mg once daily plus clarithromycin 500 mg 3 times daily for 14 days; continue omeprazole 20 mg/day for an additional 14 days if an ulcer is present at start of therapy.

Pathologic Hypersecretory Conditions
Adults

PO Initial dosage, 60 mg/day. Dosages up to 120 mg 3 times daily have been given. Divide daily doses of more than 80 mg.

General Advice

  • Administer on an empty stomach at least 1 h before a meal. Capsules and tablets should not be crushed or chewed.
  • For patients who have difficulty swallowing capsules, the contents of a delayed-release capsule can be added to a tablespoon of applesauce in a bowl. The pellets should be mixed with the applesauce and swallowed immediately with a glass of cool water. The applesauce should be soft enough to swallow without chewing and should not be heated. The omeprazole pellets should not be chewed or crushed. Do not store the pellets/applesauce mixture for future use.
  • Administer delayed-release suspension by emptying contents of a 2.5 mg packet into 5 mL of water or by emptying contents of a 10 mg packet into 15 mL of water. Stir and leave for 2 to 3 min to thicken. Stir and drink within 30 min. If any material remains after drinking, add more water, stir and drink immediately.
  • For patients with a nasogastric (NG) or gastric tube, add 5 mL of water to a catheter-tipped syringe and then add the contents of a 2.5 mg packet (or 15 mL of water for the 10 mg packet). Only use a catheter-tipped syringe when administering omeprazole through an NG or gastric tube. Immediately shake the syringe and allow 2 to 3 min to thicken. Shake the syringe and inject contents through the nasogastric or gastric tube into the stomach within 30 min, using a French size 6 or larger. Refill the syringe with an equal amount of water, shake, and flush any remaining contents from the NG or gastric tube into the stomach.

Storage/Stability

Store capsules and packets for delayed-release oral suspension between 59° and 86°F. Store capsules between 59° and 86°F; protect from light and moisture. Store tablets between 68° and 77°F; keep out of high heat and humidity and protect from moisture.

Drug Interactions

Ampicillin

The inhibition of gastric acid secretion may interfere with the absorption of ampicillin esters in which gastric pH is an important determinant of bioavailability. Temporary cessation of omeprazole treatment may be required in order to achieve the appropriate clinical response to ampicillin.

Atazanavir, nelfinavir, ritonavir

Plasma concentrations may be reduced by omeprazole, decreasing the efficacy. Coadministration with omeprazole is not recommended.

Azole antifungal agents (eg, itraconazole, ketoconazole)

The bioavailability of certain azole antifungals may be decreased. Avoid coadministration if possible. If concurrent use cannot be avoided, consider instructing the patient to take with an acidic beverage (eg, Coca-Cola ) to help increase azole antifungal absorption.

Benzodiazepines (eg, diazepam)

Cl of benzodiazepines may be decreased. Monitor for increased CNS impairment and reduce the benzodiazepine dosage or increase the dosing interval if needed. Benzodiazepines not metabolized by oxidation (eg, lorazepam) may not interact.

Calcium salts

Omeprazole may decrease GI absorption of calcium salts. Closely monitor the clinical response to calcium salts. Larger dosages of calcium salts may be needed for patients taking long-term omeprazole.

Carbamazepine

Carbamazepine plasma concentrations may be elevated, increasing the risk of toxicity. Additional carbamazepine concentration and clinical monitoring is warranted. Adjust the carbamazepine dose as needed when starting or stopping omeprazole.

Cilostazol, tacrolimus

Plasma levels may be increased by omeprazole, increasing the therapeutic effects and adverse reactions. Consider dosage adjustment of cilostazol from 100 to 50 mg twice daily. Monitor tacrolimus trough concentrations when omeprazole is started or stopped. Adjust the tacrolimus dose as needed.

Clarithromycin

Omeprazole and clarithromycin plasma concentrations may be elevated. Based upon available data, no special action is needed.

Clopidogrel

Controlled studies are needed to determine the magnitude of this interaction with each proton pump inhibitor (PPI) and clopidogrel. The antiplatelet activity of clopidogrel may be decreased by omeprazole. Omeprazole may interfere with the metabolic (CYP2C19) conversion of clopidogrel to its active metabolite. If omeprazole is clearly indicated in a patient receiving clopidogrel, use with caution. An antacid or H 2 receptor antagonist (eg, ranitidine) may be a safer alternative.

Clozapine

Clozapine plasma concentrations and pharmacologic effects may be increased. Clozapine toxicity may occur. Close clinical and laboratory monitoring is warranted. Adjust the clozapine dose as needed.

Dasatinib, erlotinib, nilotinib

Omeprazole may interfere with the absorption of these agents. Plasma concentration and pharmacologic effects of these agents may be decreased. Avoid coadministration with omeprazole.

Digoxin

Coadministration may increase serum digoxin concentrations. The magnitude of this change would not be expected to be clinically important in most patients.

Disulfiram

The neuropsychiatric toxicity of disulfiram may be increased. The clinical importance of this interaction is not known. If an interaction is suspected, it may be necessary to discontinue both drugs.

Fluvoxamine

Omeprazole plasma concentrations may be elevated, increasing the risk of adverse reactions. Monitor for an increase in adverse reactions.

Food

Administration of omeprazole with applesauce may decrease the omeprazole C max with a change in the AUC. The clinical importance is unknown. It is recommended that omeprazole capsules be administered before meals.

Ginkgo biloba , St. John's wort

Omeprazole plasma concentrations may be reduced, decreasing the therapeutic effect. Avoid concurrent use.

Hydantoins (eg, phenytoin)

Decreased plasma Cl and increased phenytoin half-life. Serum hydantoin levels may be elevated, increasing the pharmacologic effects and risk of toxicity. Observe the patient for adverse effects and monitor phenytoin serum concentrations. Adjust the hydantoin dose as needed.

Iron salts

The inhibition of gastric acid secretion may interfere with the absorption of drugs in which gastric pH is an important determinant of bioavailability. Temporary cessation of omeprazole treatment may be required in order to achieve the appropriate clinical response to oral iron. If stopping omeprazole is not an option, parenteral iron may be a suitable alternative.

Methotrexate

Omeprazole may decrease the renal elimination of methotrexate, increasing methotrexate concentrations and the risk of toxicity. Closely monitor methotrexate concentrations and monitor for signs of methotrexate toxicity. Longer duration of leucovorin rescue, systemic hydration, and urinary alkalinization may be required for high-dose methotrexate. Consider discontinuing or suspending omeprazole.

Mycophenolate

Mycophenolate plasma concentrations and pharmacologic effects may be decreased. Larger mycophenolate doses may be needed during coadministration of omeprazole. Monitor the clinical response and adjust the mycophenolate dose as needed.

Propranolol

Although no interaction with propranolol and omeprazole has been reported, interactions have been reported with other drugs metabolized by the CYP-450 system. Clinical and laboratory monitoring of propranolol is warranted. Adjust the propranolol dose as needed.

Salicylates

Enteric-coated salicylates may dissolve more rapidly, increasing gastric adverse effects. Patients at risk of serious gastric disorders due to the release of salicylates in the stomach should avoid concurrent use of these agents.

Saquinavir

Plasma concentrations may be elevated by omeprazole, increasing the risk of adverse reactions. Consider saquinavir dose reduction.

Theophylline

The rate of theophylline absorption from slow-release forms of theophylline may be increased. In addition, interactions have been reported with other drugs metabolized by the CYP-450 system. Clinical and laboratory monitoring is warranted. Adjust the theophylline dose as needed.

Tolterodine ER

An increase in the release of tolterodine from the ER dosage form may occur as a result of the increase in gastric pH associated with PPI administration. Plasma concentrations of tolterodine and its active metabolite may be elevated, increasing the pharmacologic effects and risk of adverse reactions. Monitor the clinical response and for adverse reactions. Adjust the tolterodine dose as needed.

Voriconazole

Omeprazole plasma concentrations may be elevated, which may necessitate dosage adjustments in patients with Zollinger-Ellison syndrome.

Warfarin

Increased INR and PT, which may lead to abnormal bleeding and increase the risk of death. Monitor anticoagulant parameters when starting or stopping omeprazole and adjust the warfarin dose as needed.

Adverse Reactions

Cardiovascular

Angina or chest pain, bradycardia, elevated BP, palpitations, peripheral edema, tachycardia (postmarketing).

CNS

Headache (7%); dizziness (2%); asthenia (1%); abnormal dreams, aggression, agitation, anxiety, apathy, confusion, depression, fatigue, hallucinations, insomnia, malaise, nervousness, paresthesia, sleep disturbances, somnolence, tremors, vertigo (postmarketing).

Dermatologic

Rash (2%); alopecia, dry skin, erythema multiforme, hyperhidrosis, petechiae, photosensitivity, pruritus, purpura, skin inflammation, Stevens-Johnson syndrome, TEN, urticaria (postmarketing).

EENT

Anterior ischemic optic neuropathy, blurred vision, double vision, dry eye syndrome, ocular irritation, optic atrophy, optic neuritis, pharyngeal pain, taste perversion, tinnitus (postmarketing).

GI

Abdominal pain (5%); diarrhea, nausea (4%); flatulence, vomiting (3%); acid regurgitation, constipation (2%); abdominal swelling, anorexia, dry mouth, esophageal candidiasis, fecal discoloration, gastric fundic gland polyps, gastroduodenal carcinoids, irritable colon, mucosal atrophy of the tongue, pancreatitis, stomatitis (postmarketing).

Genitourinary

Elevated serum creatinine, glucosuria, gynecomastia, hematuria, interstitial nephritis, microscopic pyuria, proteinuria, testicular pain, urinary frequency, UTI (postmarketing).

Hepatic

Cholestatic disease, elevated LFTs (alkaline phosphatase, bilirubin, ALT, AST, GGT), hepatic encephalopathy, hepatic failure (some fatal), hepatocellular disease, jaundice, liver necrosis, mixed hepatitis (postmarketing).

Hematologic-Lymphatic

Agranulocytosis, anemia, hemolytic anemia, leukocytosis, leukopenia, neutropenia, pancytopenia, thrombocytopenia (postmarketing).

Hypersensitivity

Anaphylactic shock, anaphylaxis, angioedema, bronchospasm, interstitial nephritis, urticaria (postmarketing).

Metabolic-Nutritional

Hypoglycemia, hypomagnesemia, hyponatremia, weight gain (postmarketing).

Musculoskeletal

Back pain (1%); bone fracture, joint pain, leg pain, muscle cramps, muscle weakness, myalgia (postmarketing).

Respiratory

Upper respiratory tract infection (2%); cough (1%); epistaxis (postmarketing).

Miscellaneous

Fever (children 1 to 2 y of age, 33%); pain (postmarketing).

Precautions

Pregnancy

Category C .

Lactation

Excreted in breast milk. Make a decision whether to discontinue breast-feeding or the drug.

Children

Safety and efficacy not established for the treatment of GERD in children younger than 1 y of age. Safety and efficacy for other uses not established.

Elderly

Greater sensitivity of some older individuals cannot be ruled out.

Hypersensitivity

Reactions may include anaphylaxis, anaphylactic shock, angioedema, bronchospasm, interstitial nephritis, and urticaria.

Hepatic Function

Consider dosage adjustment in patients with hepatic impairment, especially for maintenance of healing of erosive esophagitis.

Atrophic gastritis

Has been reported in gastric corpus biopsies in patients treated with long-term omeprazole.

Bone fracture

PPI therapy may be associated with an increased risk for osteoporosis-related fracture of the hip, wrist, or spine, especially in patients receiving high-dose and long-term (1 y or longer) therapy. Use the lowest dose and shortest duration of PPI therapy appropriate to the condition being treated.

Concomitant gastric malignancy

Symptomatic response to therapy with omeprazole does not preclude the presence of gastric malignancy.

Overdosage

Symptoms

Blurred vision, confusion, diaphoresis, drowsiness, dry mouth, flushing, headache, nausea, tachycardia, vomiting.

Patient Information

  • Instruct patient using OTC omeprazole tablets to carefully read the package instructions regarding warnings and dosing instructions. Advise patient to swallow tablet whole and not to split, crush, or chew tablet.
  • Instruct patient to take each dose on an empty stomach at least 1 h before eating.
  • Instruct patient to swallow capsules whole and not to open, crush, or chew the capsule.
  • Advise patients having difficulty swallowing the capsule to open it and gently mix the pellets with 1 Tbsp of cool or cold applesauce and then immediately swallow the mixture without chewing. Remind patients not to crush or chew the pellets and not to prepare the pellet/applesauce mixture ahead of time or store for future use.
  • Instruct patients using oral suspension to empty the contents of a 2.5 mg packet into a container containing 5 mL of water, or empty the contents of a 10 mg packet into a container containing 15 mL of water. Stir. Leave for 2 to 3 min to thicken. Stir and drink within 30 min. If any material remains after drinking, add more water, stir, and drink immediately.
  • Instruct patients with NG or gastric tubes using oral suspension to add 5 mL of water to a catheter-tipped syringe and then add the contents of a 2.5 mg packet (or 15 mL of water for the 10 mg packet). Inform patients that it is important to only use a catheter-tipped syringe when administering omeprazole through an NG tube or gastric tube. Immediately shake the syringe and leave for 2 to 3 min to thicken. Shake the syringe and inject through the NG or gastric tube, French size 6 or larger, into the stomach within 30 min. Refill the syringe with an equal amount of water. Shake and flush any remaining contents from the nasogastric tube into the stomach.
  • Remind patients that omeprazole is to be taken every day, not as needed or only when symptoms are present.
  • Advises patient that this drug may take 1 to 4 days for full effect to be seen.
  • Inform patients that antacids may be taken concurrently with omeprazole.
  • Instruct patients to report any of the following to health care provider: bloody or coffee ground–like vomit; black, tarry stools; recurrent heartburn; recurrent indigestion or abdominal pain; increasing need for antacid use; bothersome side effects (eg, headache, constipation, gas).

Copyright © 2009 Wolters Kluwer Health.

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