Included as part of the PRECAUTIONS section.

Concomitant Gastric Malignancy

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

Atrophic gastritis

Atrophic gastritis has been noted occasionally in gastric corpus biopsies from patients treated long-term with omeprazole.

Buffer Content

Each ZEGERID Capsule contains 1100 mg (13 mEq) of sodium bicarbonate. The total content of sodium in each capsule is 304 mg.

Each packet of ZEGERID Powder for Oral Suspension contains 1680 mg (20 mEq) of sodium bicarbonate (equivalent to 460 mg of Na+).

The sodium content of ZEGERID products should be taken into consideration when administering to patients on a sodium restricted diet.

Because ZEGERID products contain sodium bicarbonate, they should be used with caution in patients with Bartter's syndrome, hypokalemia, hypocalcemia, and problems with acid-base balance. Long-term administration of bicarbonate with calcium or milk can cause milk-alkali syndrome.

Chronic use of sodium bicarbonate may lead to systemic alkalosis and increased sodium intake can produce edema and weight increase.

Clostridium difficile associated diarrhea

Published observational studies suggest that PPI therapy like Zegerid may be associated with an increased risk of Clostridium difficile associated diarrhea, especially in hospitalized patients. This diagnosis should be considered for diarrhea that does not improve. [See ADVERSE REACTIONS]

Patients should use the lowest dose and shortest duration of PPI therapy appropriate to the condition being treated.

Interaction with clopidogrel

Avoid concomitant use of Zegerid with clopidogrel. Clopidogrel is a prodrug. Inhibition of platelet aggregation by clopidogrel is entirely due to an active metabolite. The metabolism of clopidogrel to its active metabolite can be impaired by use with concomitant medications, such as omeprazole, that interfere with CYP2C19 activity. Concomitant use of clopidogrel with 80 mg omeprazole reduces the pharmacological activity of clopidogrel, even when administered 12 hours apart. When using Zegerid, consider alternative anti-platelet therapy [see DRUG INTERACTIONS and Pharmacokinetics].

Bone Fracture

Several published observational studies suggest that proton pump inhibitor (PPI) therapy may be associated with an increased risk for osteoporosis-related fractures of the hip, wrist, or spine. The risk of fracture was increased in patients who received high-dose, defined as multiple daily doses, and long-term PPI therapy (a year or longer). Patients should use the lowest dose and shortest duration of PPI therapy appropriate to the condition being treated. Patients at risk for osteoporosis-related fractures should be managed according to the established treatment guidelines. [See DOSAGE AND ADMINISTRATION and ADVERSE REACTIONS]

Hypomagnesemia

Hypomagnesemia, symptomatic and asymptomatic, has been reported rarely in patients treated with PPIs for at least three months, in most cases after a year of therapy. Serious adverse events include tetany, arrhythmias, and seizures. In most patients, treatment of hypomagnesemia required magnesium replacement and discontinuation of the PPI.

For patients expected to be on prolonged treatment or who take PPIs with medications such as digoxin or drugs that may cause hypomagnesemia (e.g., diuretics), health care professionals may consider monitoring magnesium levels prior to initiation of PPI treatment and periodically. [See ADVERSE REACTIONS]

Concomitant use of Zegerid with St John's Wort or rifampin

Drugs which induce CYP2C19 OR CYP34A (such as St John's Wort or rifampin) can substantially decrease omeprazole concentrations. [See DRUG INTERACTIONS]. Avoid concomitant use of ZEGERD with St John's Wort or rifampin.

Interactions with Investigations for Neuroendocrine Tumors

Serum chromogranin A (CgA) levels increase secondary to drug-induced decreases in gastric acidity. The increased CgA level may cause false positive results in diagnostic investigations for neuroendocrine tumors. Providers should temporarily stop omeprazole treatment before assessing CgA levels and consider repeating the test if initial CgA levels are high. If serial tests are performed (e.g. for monitoring), the same commercial laboratory should be used for testing, as reference ranges between tests may vary. [See Pharmacodynamics]

Concomitant use of Zegerid with Methotrexate

Literature suggests that concomitant use of PPIs with methotrexate (primarily at high dose; see methotrexate prescribing information) may elevate and prolong serum levels of methotrexate and/or its metabolite, possibly leading to methotrexate toxicities. In high-dose methotrexate administration, a temporary withdrawal of the PPI may be considered in some patients. [See DRUG INTERACTIONS]

Patient Counseling Information

See FDA-Approved Medication Guide.

Instruct patients that ZEGERID should be taken on an empty stomach at least one hour prior to a meal. [See DOSAGE AND ADMINISTRATION]

Instruct patients in Directions for Use as follows:

Capsules: Swallow intact capsule with water. DO NOT USE OTHER LIQUIDS. DO NOT OPEN CAPSULE AND SPRINKLE CONTENTS INTO FOOD.

Powder for Oral Suspension: Empty packet contents into a small cup containing 1-2 tablespoons of water. DO NOT USE OTHER LIQUIDS OR FOODS. Stir well and drink immediately. Refill cup with water and drink.

ZEGERID is available either as 40 mg or 20 mg capsules with 1100 mg sodium bicarbonate. ZEGERID is also available either as 40 mg or 20 mg single-dose packets of powder for oral suspension with 1680 mg sodium bicarbonate.

Patients should be instructed not to substitute Zegerid Capsules or Suspension for other ZEGERID dosage forms because different dosage forms contain different amounts of sodium bicarbonate and magnesium hydroxide. [See DOSAGE AND ADMINISTRATION]

Patients should be advised that since both the 20 mg and 40 mg oral suspension packets contain the same amount of sodium bicarbonate (1680 mg), two packets of 20 mg are not equivalent to one packet of ZEGERID 40 mg; therefore, two 20 mg packets of ZEGERID should not be substituted for one packet of ZEGERID 40 mg. Conversely ½ of a 40mg packet should not be substituted for one 20mg packet. [See DOSAGE AND ADMINISTRATION]

Patients should be advised that since both the 20 mg and 40 mg capsules contain the same amount of sodium bicarbonate (1100 mg), two capsules of 20 mg are not equivalent to one capsule of ZEGERID 40 mg; therefore, two 20 mg capsules of ZEGERID should not be substituted for one capsule of ZEGERID 40 mg. [See DOSAGE AND ADMINISTRATION]

Patients should be advised that this drug is not approved for use in patients less than 18 years of age. [See Pediatric Use]

Patients on a sodium-restricted diet or patients at risk of developing congestive heart failure (CHF) should be informed of the sodium content of ZEGERID Capsules (304 mg per capsule) and ZEGERID Powder (460 mg per packet). Patients should be informed that chronic use of sodium bicarbonate may cause problems and increased sodium intake can cause swelling and weight gain. If this occurs, they should contact their healthcare provider. [See WARNINGS AND PRECAUTIONS]

Patients should be informed that the most frequent adverse reactions associated with ZEGERID include headache, abdominal pain, nausea, diarrhea, vomiting and flatulence. [See ADVERSE REACTIONS]

Pregnant women should be advised that a harmful effect of ZEGERID on the fetus cannot be ruled out and that the drug should be used with caution during pregnancy. [See Pregnancy]

Patients should be advised to use this drug with caution if they are regularly taking calcium supplements. [See WARNINGS AND PRECAUTIONS]

Advise patients to immediately report and seek care for diarrhea that does not improve. This may be a sign of Clostridium difficile associated diarrhea [see WARNINGS AND PRECAUTIONS].

Advise patients to immediately report and seek care for any cardiovascular or neurological symptoms including palpitations, dizziness, seizures and tetany as these may be signs of hypomagnesemia. [See WARNINGS AND PRECAUTIONS]

Nonclinical Toxicology

Carcinogenesis, Mutagenesis, Impairment of Fertility

In two 24-month carcinogenicity studies in rats, omeprazole at daily doses of 1.7, 3.4, 13.8, 44.0 and 140.8 mg/kg/day (approximately 0.35 to 28.5 times the human dose of 40 mg/day, based on body surface area) produced gastric ECL cell carcinoids in a dose-related manner in both male and female rats; the incidence of this effect was markedly higher in female rats, which had higher blood levels of omeprazole. Gastric carcinoids seldom occur in the untreated rat. In addition, ECL cell hyperplasia was present in all treated groups of both sexes. In one of these studies, female rats were treated with 13.8 mg omeprazole/kg/day (approximately 2.8 times the human dose of 40 mg/day, based on body surface area) for one year, then followed for an additional year without the drug. No carcinoids were seen in these rats. An increased incidence of treatment-related ECL cell hyperplasia was observed at the end of one year (94% treated versus 10% controls). By the second year the difference between treated and control rats was much smaller (46% versus 26%) but still showed more hyperplasia in the treated group. Gastric adenocarcinoma was seen in one rat (2%). No similar tumor was seen in male or female rats treated for two years. For this strain of rat no similar tumor has been noted historically, but a finding involving only one tumor is difficult to interpret. In a 52-week toxicity study in Sprague-Dawley rats, brain astrocytomas were found in a small number of males that received omeprazole at dose levels of 0.4, 2, and 16 mg/kg/day (about 0.1 to 3.3 times the human dose of 40 mg/day, based on body surface area). No astrocytomas were observed in female rats in this study. In a 2-year carcinogenicity study in Sprague-Dawley rats, no astrocytomas were found in males and females at the high dose of 140.8 mg/kg/day (about 28.5 times the human dose of 40 mg/day, based on body surface area). A 78-week mouse carcinogenicity study of omeprazole did not show increased tumor occurrence, but the study was not conclusive. A 26-week p53 (+/-) transgenic mouse carcinogenicity study was not positive.

Omeprazole was positive for clastogenic effects in an in vitro human lymphocyte chromosomal aberration assay, in one of two in vivo mouse micronucleus tests, and in an in vivo bone marrow cell chromosomal aberration assay. Omeprazole was negative in the in vitro Ames Test, an in vitro mouse lymphoma cell forward mutation assay and an in vivo rat liver DNA damage assay.

In 24-month carcinogenicity studies in rats, a dose-related significant increase in gastric carcinoid tumors and ECL cell hyperplasia was observed in both male and female animals [See WARNINGS AND PRECAUTIONS]. Carcinoid tumors have also been observed in rats subjected to fundectomy or long-term treatment with other proton pump inhibitors or high doses of H2-receptor antagonists.

Omeprazole at oral doses up to 138 mg/kg/day (about 28 times the human dose of 40 mg/day, based on body surface area) was found to have no effect on the fertility and general reproductive performance in rats.

Use In Specific Populations

Pregnancy

Pregnancy Category C

There are no adequate and well-controlled studies on the use of omeprazole in pregnant women. The vast majority of reported experience with omeprazole during human pregnancy is first trimester exposure and the duration of use is rarely specified, eg, intermittent versus chronic. An expert review of published data on experiences with omeprazole use during pregnancy by TERIS – the Teratogen Information System – concluded that therapeutic doses during pregnancy are unlikely to pose a substantial teratogenic risk (the quantity and quality of data were assessed as fair).¹

Three epidemiological studies compared the frequency of congenital abnormalities among infants born to women who used omeprazole during pregnancy to the frequency of abnormalities among infants of women exposed to H2-receptor antagonists or other controls. A population-based prospective cohort epidemiological study from the Swedish Medical Birth Registry, covering approximately 99% of pregnancies, reported on 955 infants (824 exposed during the first trimester with 39 of these exposed beyond first trimester, and 131 exposed after the first trimester) whose mothers used omeprazole during pregnancy.² In utero exposure to omeprazole was not associated with increased risk of any malformation (odds ratio 0.82, 95% CI 0.50-1.34), low birth weight or low Apgar score. The number of infants born with ventricular septal defects and the number of stillborn infants was slightly higher in the omeprazole exposed infants than the expected number in the normal population. The author concluded that both effects may be random.

A retrospective cohort study reported on 689 pregnant women exposed to either H2-blockers or omeprazole in the first trimester (134 exposed to omeprazole).³ The overall malformation rate was 4.4% (95% CI 3.6-5.3) and the malformation rate for first trimester exposure to omeprazole was 3.6% (95% CI 1.5-8.1). The relative risk of malformations associated with first trimester exposure to omeprazole compared with nonexposed women was 0.9 (95% CI 0.3-2.2). The study could effectively rule out a relative risk greater than 2.5 for all malformations. Rates of preterm delivery or growth retardation did not differ between the groups.

A controlled prospective observational study followed 113 women exposed to omeprazole during pregnancy (89% first trimester exposures).⁴ The reported rates of major congenital malformations was 4% for the omeprazole group, 2% for controls exposed to nonteratogens, and 2.8% in disease-paired controls (background incidence of major malformations 1-5%). Rates of spontaneous and elective abortions, preterm deliveries, gestational age at delivery, and mean birth weight did not differ between the groups. The sample size in this study has 80% power to detect a 5-fold increase in the rate of major malformation.

Several studies have reported no apparent adverse short term effects on the infant when single dose oral or intravenous omeprazole was administered to over 200 pregnant women as premedication for cesarean section under general anesthesia.

Reproduction studies conducted with omeprazole in rats at oral doses up to 28 times the human dose of 40 mg/day (based on body surface area) and in rabbits at doses up to 28 times the human dose (based on body surface area) did not show any evidence of teratogenicity. In pregnant rabbits, omeprazole at doses about 2.8 to 28 times the human dose of 40 mg/day, (based on body surface area) produced dose-related increases in embryo-lethality, fetal resorptions, and pregnancy loss. In rats treated with omeprazole at doses about 2.8 to 28 times the human dose (based on body surface area), dose-related embryo/fetal toxicity and postnatal developmental toxicity occurred in offspring. [See Animal Toxicology and/or Pharmacology].

There are no adequate and well-controlled studies in pregnant women. Because animal studies and studies in humans cannot rule out the possibility of harm, ZEGERID should be used during pregnancy only if the potential benefit to pregnant women justifies the potential risk to the fetus.

Nursing Mothers

Omeprazole concentrations have been measured in breast milk of a woman following oral administration of 20 mg. The peak concentration of omeprazole in breast milk was less than 7% of the peak serum concentration. The concentration will correspond to 0.004 mg of omeprazole in 200 mL of milk. Because omeprazole is excreted in human milk, because of the potential for serious adverse reactions in nursing infants from omeprazole, and because of the potential for tumorigenicity shown for omeprazole in rat carcinogenicity studies, a decision should be made to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother. In addition, sodium bicarbonate should be used with caution in nursing mothers.

Pediatric Use

Safety and effectiveness of ZEGERID have not been established in pediatric patients less than 18 years of age.

Geriatric Use

Omeprazole was administered to over 2000 elderly individuals (≥ 65 years of age) in clinical trials in the U.S. and Europe. There were no differences in safety and effectiveness between the elderly and younger subjects. Other reported clinical experience has not identified differences in response between the elderly and younger subjects, but greater sensitivity of some older individuals cannot be ruled out.

Pharmacokinetic studies with buffered omeprazole have shown the elimination rate was somewhat decreased in the elderly and bioavailability was increased. The plasma clearance of omeprazole was 250 mL/min (about half that of young subjects). The plasma half-life averaged one hour, about twice that in nonelderly, healthy subjects taking ZEGERID. However, no dosage adjustment is necessary in the elderly. [See CLINICAL PHARMACOLOGY]

Hepatic Impairment

Consider dose reduction, particularly for maintenance of healing of erosive esophagitis. [See CLINICAL PHARMACOLOGY]

Renal Impairment

No dose reduction is necessary. [See CLINICAL PHARMACOLOGY]

Asian Population

Recommend dose reduction, particularly for maintenance of healing of erosive esophagitis. [See CLINICAL PHARMACOLOGY]

REFERENCES

1. Friedman JM and Polifka JE. Omeprazole. In: Teratogenic Effects of Drugs. A Resource for Clinicians (TERIS). 2nd ed. Baltimore, MD: The Johns Hopkins University Press 2000; p. 516.

2. Kallen BAJ. Use of omeprazole during pregnancy – no hazard demonstrated in 955 infants exposed during pregnancy. Eur Obstet Gynecol Reprod Biol 2001; 96(1):63-8.

3. Ruigómez A, Rodriquez LUG, Cattaruzzi C, et al. Use of cimetidine, omeprazole, and ranitidine in pregnant women and pregnancy outcomes. Am J Epidemiol 1999; 150: 476-81.

4. Lalkin A, Loebstein, Addis A, et al. The safety of omeprazole during pregnancy: a multicenter prospective controlled study. Am J Obstet Gynecol 1998: 179:727-30.

Last reviewed on RxList: 12/11/2012
This monograph has been modified to include the generic and brand name in many instances.