Omez

INSTRUCTION FOR MEDICAL USE OF THE MEDICINAL PRODUCT OMEZ® (OMEZ)

Composition:

Active substance: omeprazole;

1 vial contains omeprazole sodium equivalent to omeprazole 40 mg;

Excipient: sodium carbonate anhydrous.

Pharmaceutical form. Lyophilisate for solution for injection.

Main physicochemical properties: lyophilized powder ranging from white to light yellow, without visible inclusions.

Pharmacotherapeutic group.

Agents for treatment of peptic ulcer and gastroesophageal reflux disease. Proton pump inhibitors. Omeprazole. ATC code A02BC01.

Pharmacological properties.

Pharmacodynamics.

Mechanism of action

Omeprazole, a racemic mixture of two enantiomers, reduces gastric hydrochloric acid secretion through a highly targeted mechanism of action. Omeprazole inhibits gastric acid secretion by specifically acting on the proton pump in parietal cells. When administered once daily, the drug acts rapidly and provides control through reversible inhibition of gastric acid secretion.

Omeprazole is a weak base that accumulates and is converted into its active form in the highly acidic environment of the intracellular canaliculi of parietal cells, where it inhibits the H⁺, K⁺-ATPase enzyme (proton pump). This effect at the final stage of gastric acid formation is dose-dependent and results in highly effective suppression of both basal and stimulated acid secretion, regardless of the type of stimulation.

Pharmacodynamic effects

All pharmacodynamic effects can be explained by the influence of omeprazole on gastric acid secretion.

Effect on gastric acid secretion

Intravenous administration of omeprazole causes dose-dependent inhibition of gastric acid secretion in humans. To achieve an immediate reduction in intragastric acidity equivalent to that obtained with repeated oral doses of 20 mg, an initial intravenous dose of 40 mg is recommended. This leads to an immediate reduction in intragastric acidity and sustained suppression, on average by 90%, over 24 hours, whether administered by intravenous injection or infusion.

Inhibition of gastric acid secretion correlates with the area under the plasma concentration-time curve (AUC) of omeprazole and does not depend on the current plasma concentration of omeprazole at any given time.

No signs of tachyphylaxis have been observed during omeprazole treatment.

Effect on Helicobacter pylori (H. pylori)

H. pylori is associated with the development of peptic ulcer disease, including duodenal and gastric ulcers. H. pylori is a primary cause of gastritis. H. pylori, together with gastric hydrochloric acid, is a major factor in the development of peptic ulcer disease. H. pylori is also a primary factor in the development of atrophic gastritis, which is associated with an increased risk of gastric cancer.

Eradication of H. pylori using omeprazole in combination with antimicrobial agents is associated with high healing rates and prolonged remission of peptic ulcer disease.

Other effects related to inhibition of gastric acid secretion

During treatment with antisecretory drugs, serum gastrin levels increase in response to reduced acid secretion. Additionally, due to decreased gastric acidity, chromogranin A (CgA) levels rise. Elevated CgA levels may interfere with diagnostic testing for neuroendocrine tumors. It has been reported that treatment with proton pump inhibitors (PPIs) should be discontinued 5–14 days before CgA measurement. Testing should be repeated if levels have not normalized by that time.

An increase in ECL-cell numbers, possibly related to elevated serum gastrin levels, has been observed in both children and adults during long-term omeprazole treatment. These findings are considered to have no clinical significance.

During prolonged treatment courses, a slightly increased frequency of gastric fundic gland polyps has been reported. These changes are a physiological consequence of pronounced inhibition of gastric acid secretion; the process is benign and likely reversible.

Reduction of gastric acidity by any means, including PPIs, increases the number of bacteria normally present in the gastrointestinal tract. Treatment with acid-reducing agents slightly increases the risk of gastrointestinal infections caused by Salmonella and Campylobacter.

Pharmacokinetics.

Distribution

The apparent volume of distribution is approximately 0.3 L/kg body weight. Omeprazole is approximately 97% bound to plasma proteins.

Metabolism and elimination

Omeprazole is completely metabolized by the cytochrome P450 (CYP) system. The majority of its metabolism depends on the polymorphically expressed CYP2C19, which is responsible for the formation of hydroxyomeprazole, the main metabolite in plasma. The remainder depends on another specific isoenzyme (CYP3A4), responsible for the formation of omeprazole sulfone. Due to omeprazole's high affinity for CYP2C19, there is potential for competitive inhibition and metabolic drug-drug interactions with other CYP2C19 substrates. However, due to its low affinity for CYP3A4, omeprazole does not have the ability to inhibit the metabolism of other CYP3A4 substrates. Furthermore, omeprazole does not exert inhibitory effects on major CYP enzymes.

Approximately 3% of individuals of Caucasian ethnicity and 15–20% of individuals of Mongoloid ethnicity lack functional CYP2C19 enzyme; they are referred to as "poor metabolizers." In these individuals, omeprazole metabolism may be primarily catalyzed by the CYP3A4 enzyme. After repeated administration of omeprazole at 20 mg once daily, the mean AUC in "poor metabolizers" is 5–10 times higher than in individuals with functional CYP2C19 enzyme ("extensive metabolizers"). Mean maximum plasma concentrations are also 3–5 times higher. However, these findings do not affect omeprazole dosing.

Elimination

Total plasma clearance is approximately 30–40 L/hour after a single dose. The elimination half-life of omeprazole in plasma is usually less than 1 hour, both after single and repeated once-daily dosing. Omeprazole is completely cleared from plasma between doses, with no tendency for accumulation when administered once daily. Nearly 80% of an omeprazole dose is excreted in urine as metabolites, and the remainder is excreted in feces, primarily via biliary secretion.

The AUC of omeprazole increases with repeated administration. This increase is dose-dependent and results in a nonlinear relationship between AUC and dose after repeated dosing. This time- and dose-dependent relationship is attributed to reduced presystemic metabolism and systemic clearance, possibly due to inhibition of the CYP2C19 enzyme by omeprazole and/or its metabolites (e.g., sulfone). No effects of any metabolites on gastric acid secretion have been demonstrated.

Special patient populations

Patients with hepatic impairment

Metabolism of omeprazole is slowed in patients with impaired liver function, leading to increased AUC. However, with once-daily administration of omeprazole, no tendency toward drug accumulation has been observed.

Patients with renal impairment

The pharmacokinetics of omeprazole, including systemic bioavailability and elimination rate, are unchanged in patients with impaired renal function.

Elderly patients

The rate of omeprazole metabolism is slightly reduced in elderly patients (75–79 years of age).

Clinical characteristics.

Indications.

Intravenous omeprazole is indicated as an alternative to oral therapy in the following cases.

Adults

Treatment of duodenal ulcer.

Prevention of recurrence of duodenal ulcer.

Treatment of gastric ulcer.

Prevention of recurrence of gastric ulcer.

In combination with appropriate antibiotics for eradication of Helicobacter pylori (H. pylori) in peptic ulcer disease.

Treatment of gastric and duodenal ulcers associated with use of nonsteroidal anti-inflammatory drugs (NSAIDs).

Prevention of gastric and duodenal ulcers associated with NSAID use in patients at risk.

Treatment of reflux esophagitis.

Long-term treatment of patients with inactive reflux esophagitis.

Treatment of symptomatic gastroesophageal reflux disease.

Treatment of Zollinger–Ellison syndrome.

Contraindications.

Hypersensitivity to omeprazole, substituted benzimidazoles, or to any of the excipients of the medicinal product.

Omeprazole, like other PPIs, must not be used concomitantly with nelfinavir and atazanavir.

Interaction with other medicinal products and other forms of interactions.

Effect of omeprazole on the pharmacokinetics of other medicinal products

Medicinal products whose absorption is pH-dependent

Inhibition of gastric secretion during treatment with omeprazole and other PPIs may reduce or increase the absorption of medicinal products whose absorption is pH-dependent. As with other agents that reduce gastric acidity, absorption of drugs such as ketoconazole, itraconazole, and erlotinib may be decreased, whereas absorption of drugs such as digoxin may be increased during omeprazole treatment. Concomitant administration of omeprazole (20 mg once daily) and digoxin in healthy volunteers increased the bioavailability of digoxin by 10 % (in two out of ten subjects by up to 30 %).

Nelfinavir, atazanavir

Plasma levels of nelfinavir and atazanavir are reduced when co-administered with omeprazole.

Concomitant use of omeprazole and nelfinavir is contraindicated.

Concomitant administration of omeprazole (40 mg once daily) reduced the average exposure to nelfinavir by approximately 40 %, and average exposure to its pharmacologically active metabolite M8 was reduced by approximately 75–90 %. The interaction may also be due to inhibition of CYP2C19 activity.

Concomitant use of omeprazole with atazanavir is not recommended.

Concomitant administration of omeprazole (40 mg once daily) with atazanavir 300 mg or ritonavir 100 mg resulted in a 75 % reduction in atazanavir exposure. Increasing the atazanavir dose to 400 mg did not compensate for the effect of omeprazole on atazanavir exposure. Concomitant administration of omeprazole (20 mg once daily) with atazanavir 400 mg or ritonavir 100 mg in healthy volunteers resulted in approximately 30 % reduction in atazanavir exposure compared to atazanavir 300 mg or ritonavir 100 mg once daily.

Digoxin

Concomitant treatment with omeprazole (20 mg daily) and digoxin in healthy volunteers increased digoxin bioavailability by 10 %. Cases of digoxin-induced toxicity have been reported rarely. However, caution should be exercised when prescribing high doses of omeprazole to elderly patients. Therapeutic drug monitoring of digoxin should be intensified. When used concomitantly with digoxin, patients should be under close medical supervision.

Clopidogrel

In a study, clopidogrel (loading dose 300 mg followed by 75 mg daily) was administered alone and with omeprazole (80 mg given simultaneously with clopidogrel) for 5 days. When clopidogrel and omeprazole were used together, exposure to the active metabolite of clopidogrel decreased by 46 % (Day 1) and 42 % (Day 5). Mean inhibition of platelet aggregation was reduced by 47 % (after 24 hours) and 30 % (Day 5) when clopidogrel and omeprazole were administered together. In another study, administration of clopidogrel and omeprazole at different times did not prevent their interaction, likely due to the inhibitory effect of omeprazole on CYP2C19. Conflicting data on the clinical relevance of this pharmacokinetic/pharmacodynamic interaction regarding major cardiovascular events have been reported in observational and clinical studies. Therefore, concomitant use of omeprazole and clopidogrel should be avoided.

Other medicinal products

Absorption of posaconazole, erlotinib, ketoconazole, and itraconazole is significantly reduced, thus clinical efficacy may be diminished. Concomitant use of the medicinal product with posaconazole and erlotinib should be avoided.

Medicinal products metabolized by CYP2C19

Omeprazole is a moderate inhibitor of CYP2C19, the main enzyme responsible for omeprazole metabolism. Thus, metabolism of concomitant medicinal products metabolized by CYP2C19 may be reduced, and systemic exposure to these agents may be increased. Examples include R-warfarin and other vitamin K antagonists, cilostazol, diazepam, and phenytoin.

In healthy volunteers, a pharmacokinetic/pharmacodynamic interaction was observed between clopidogrel (loading dose 300 mg/maintenance dose 75 mg daily) and omeprazole (80 mg daily orally, i.e., a dose four times higher than the standard daily dose), resulting in a mean reduction of 46 % in exposure to the active metabolite of clopidogrel and a mean reduction of 16 % in maximum inhibitory effect (ADP-induced) of platelet aggregation. As a precautionary measure, concomitant use of omeprazole and clopidogrel should be avoided.

However, the clinical significance of this interaction remains unclear.

Cilostazol

In healthy volunteers, administration of omeprazole 40 mg increased the Cmax and AUC of cilostazol by 18 % and 26 %, respectively, and of one of its active metabolites by 29 % and 69 %, respectively.

Phenytoin

Plasma concentration monitoring of phenytoin is recommended during the first 2 weeks after initiation of omeprazole treatment; if phenytoin dosage adjustment is required, monitoring and further dose adjustments should be performed after discontinuation of omeprazole therapy.

Unknown interaction mechanism

Saquinavir

Concomitant use of omeprazole with saquinavir/ritonavir resulted in an increase in plasma levels of saquinavir by approximately 70 %, which was associated with acceptable tolerability in HIV-infected patients.

Tacrolimus

Increased serum levels of tacrolimus have been reported with concomitant use of omeprazole. Close monitoring of tacrolimus concentrations and renal function (creatinine clearance) is required, and dosage adjustment of tacrolimus may be necessary.

Metotrexate

Elevated methotrexate levels have been reported in some patients when co-administered with PPIs. If high-dose methotrexate therapy is required, temporary discontinuation of omeprazole should be considered.

Effect of other medicinal products on the pharmacokinetics of omeprazole

Inhibitors of CYP2C19 and/or CYP3A4

Since omeprazole is metabolized by CYP2C19 and CYP3A4 enzymes, medicinal products known to inhibit the activity of CYP2C19 or CYP3A4, or both enzymes (such as clarithromycin and voriconazole), may cause an increase in omeprazole plasma levels due to slowed metabolism. Concomitant administration of voriconazole resulted in more than a two-fold increase in omeprazole exposure. Since high doses of omeprazole have been well tolerated, dose adjustment of omeprazole is usually not required. However, dose adjustment should be considered for patients with severe hepatic impairment and in cases where long-term treatment is indicated.

Omeprazole is partially metabolized by CYP3A4 as well, but does not inhibit this enzyme. Therefore, omeprazole does not affect the metabolism of medicinal products metabolized by CYP3A4, such as cyclosporine, lidocaine, quinidine, estradiol, erythromycin, and budesonide.

Inducers of CYP2C19 and/or CYP3A4

Medicinal products known to induce the activity of CYP2C19 or CYP3A4, or both enzymes (such as rifampicin and St. John’s wort), may cause a decrease in omeprazole plasma levels due to accelerated metabolism.

Special precautions for use.

In the presence of any alarming symptom (e.g., significant unintentional weight loss, recurrent vomiting, dysphagia, hematemesis, or melena) and in suspected or confirmed gastric ulcer, malignancy must be excluded, as treatment may reduce symptom severity and delay diagnosis.

Concomitant use of atazanavir with PPIs is not recommended. If co-administration of atazanavir with a PPI cannot be avoided, careful clinical monitoring (e.g., viral load) is recommended in combination with increased atazanavir dose to 400 mg with 100 mg ritonavir; the omeprazole dose should not exceed 20 mg.

Omeprazole, like all medicinal products that inhibit gastric acid secretion, may reduce absorption of vitamin B12 (cyanocobalamin) due to hypo- or achlorhydria. This should be considered when treating patients with cachexia or risk factors for reduced vitamin B12 absorption during long-term therapy.

Omeprazole is an inhibitor of CYP2C19. At initiation or discontinuation of omeprazole therapy, potential interactions with medicinal products metabolized by CYP2C19 should be considered. An interaction has been observed between clopidogrel and omeprazole. The clinical significance of this interaction remains unclear. As a precautionary measure, concomitant use of omeprazole and clopidogrel should be avoided.

PPI therapy slightly increases the risk of gastrointestinal infections such as Salmonella and Campylobacter.

Use of PPIs, particularly at high doses and over prolonged periods (>1 year), is associated with a slightly increased risk of fractures of the hip, wrist, and spine, primarily in elderly patients or those with other risk factors. According to study data, PPIs increase fracture risk overall by 10–40%. In some cases, this is associated with the presence of other risk factors in the patient. Patients at risk of osteoporosis should receive appropriate treatment and adequate supplementation with vitamin D and calcium.

As with any long-term therapy, especially when omeprazole treatment exceeds one year, patients require medical supervision and regular laboratory monitoring of serum magnesium and calcium levels.

In patients receiving PPIs, including omeprazole, for at least 3 months, clinically significant hypomagnesemia may occur (in most cases, patients had been taking the drug for approximately 1 year).

After discontinuation of the drug, serum magnesium levels returned to normal. Clinical features of hypomagnesemia include increased neuromuscular excitability, manifested by carpopedal spasms, motor restlessness; tachycardia, cardiac arrhythmias, elevated blood pressure; dystrophic disorders such as trophic erosions and skin ulcers. The diagnostic criterion for hypomagnesemia is a reduction in serum magnesium concentration below 1 mEq/L. Additionally, cases have been reported where hypomagnesemia led to hypocalcemia due to suppressed parathyroid hormone secretion under conditions of low magnesium levels in the body. In some patients, severe hypocalcemia and hypomagnesemia were observed, with development of seizure syndrome, cardiac rhythm disturbances, tetany, mental disorders, and severe vomiting, leading to electrolyte imbalance.

During treatment with antisecretory agents, plasma gastrin concentration increases as a result of reduced gastric acid secretion. Due to decreased acid secretion, chromogranin A (CgA) levels increase. Elevated CgA levels may interfere with diagnostic tests for neuroendocrine tumors. To prevent such interference, PPIs should be discontinued at least 5 days before measuring CgA levels. If CgA and gastrin levels have not returned to reference values after initial measurements, testing should be repeated 14 days after discontinuation of PPI therapy.

Subacute cutaneous lupus erythematosus (SCLE)

PPI use may be associated with very rare cases of SCLE. If skin lesions develop, particularly in sun-exposed areas, and are accompanied by arthralgia, the patient should seek immediate medical attention, and the healthcare provider should consider discontinuing omeprazole. A history of SCLE following previous PPI treatment increases the risk of developing SCLE upon subsequent use of other PPIs.

Renal function impairment

Acute tubulointerstitial nephritis (TIN) has been reported in patients taking omeprazole. It may occur at any time during omeprazole therapy (see section "Adverse reactions") and may progress to renal failure. If TIN is suspected, omeprazole should be discontinued and appropriate treatment initiated immediately.

This medicinal product contains 1.93 mmol (or 44.52 mg)/dose of sodium. Caution is advised when administering this product to patients on a sodium-restricted diet.

Use during pregnancy or breastfeeding.

Epidemiological studies involving over 1000 pregnant women who had normal deliveries indicate no adverse effects of omeprazole on pregnancy or fetal/neonatal health. Omeprazole may be used during pregnancy only if, in the physician’s opinion, the expected benefit to the mother outweighs the potential risk to the fetus.

Omeprazole is excreted in breast milk in small amounts, but its effect on the infant is unknown. Therefore, breastfeeding should be discontinued during treatment with this medicinal product.

Ability to affect reaction speed when driving or operating machinery.

It is unlikely that the medicinal product affects the ability to drive a car or operate machinery.

However, considering that adverse reactions (e.g., dizziness, drowsiness, hallucinations, reversible confusion, etc.) may occur in sensitive patients during treatment, such patients should refrain from driving or operating machinery requiring concentration during treatment.

Method of Administration and Dosage

Dosage

Alternative to Oral Therapy

For patients for whom oral administration of the drug is unsuitable, it is recommended to administer omeprazole 40 mg once daily intravenously. For patients with Zollinger–Ellison syndrome, the recommended initial intravenous dose is 60 mg per day. Higher daily doses may be required; therefore, the dose should be individually adjusted. If the daily dose exceeds 60 mg, it should be divided equally into two doses and administered twice daily.

The drug should be administered only intravenously and must not be given by any other route.

The solution should be used immediately after preparation, but no later than within 3 hours. The diluted omeprazole solution must not be stored in the refrigerator. Any unused solution should be discarded.

Instructions for Reconstitution Prior to Administration

For Intravenous Injections: The contents of each vial containing 40 mg of omeprazole should be dissolved in 10 mL of sterile water for injections. The solution for intravenous injection should be administered slowly over 5 minutes.

For Intravenous Infusions: The contents of each vial containing 40 mg of omeprazole should be reconstituted with 10 mL and then diluted to 100 mL with 0.9% sodium chloride solution or 5% glucose solution. The stability of omeprazole depends on the pH of the infusion solution; therefore, other solvents or volumes should not be used for dilution.

The intravenous infusion should be administered over 20–30 minutes.

The solution should be used immediately after preparation, but no later than within 3 hours. The diluted omeprazole solution must not be stored in the refrigerator.

Any unused product or waste material should be disposed of in accordance with local requirements.

Special Patient Populations

Renal Impairment

Dose adjustment is not required in patients with renal impairment.

Hepatic Impairment

In patients with hepatic impairment, a daily dose of 10–20 mg may be sufficient.

Elderly Patients (> 65 years)

Dose adjustment is not required in elderly patients.

Children

Experience with intravenous administration of the drug in pediatric practice is limited; therefore, the drug should not be prescribed to this patient group.

Overdose

Information on the consequences of omeprazole overdose in humans is limited. Cases of administration up to 560 mg have been reported. There have also been isolated reports of single oral doses of omeprazole reaching 2400 mg (120 times higher than the usual recommended clinical dose). Symptoms such as nausea, vomiting, dizziness, abdominal pain, diarrhea, and headache have been observed. In isolated cases, apathy, depression, and confusion have also been reported.

The described symptoms were transient, and no reports of serious consequences have been received. The elimination rate of the drug did not change (first-order kinetics) with increasing doses.

In clinical studies, intravenous administration of up to 270 mg in a single day and up to 650 mg over three days did not result in any dose-dependent adverse reactions.

Treatment: There is no specific antidote. The drug is poorly removed by dialysis. Gastric lavage, symptomatic, and supportive therapy are indicated.

Adverse reactions.

The most common adverse reactions are headache, abdominal pain, constipation, diarrhea, flatulence, and nausea/vomiting.

The undesirable effects listed below were identified during clinical studies. None of these events were considered dose-dependent.

In isolated cases, irreversible vision impairment has been reported in critically ill patients receiving intravenous omeprazole, particularly at high doses; however, a causal relationship has not been established.

The profile of adverse reactions observed in children corresponds to that in adults, both during short-term and long-term therapy.

Shelf life. 2 years.

Vials containing powder (without cardboard packaging) may be stored under normal lighting conditions for up to 24 hours.

Reconstituted solution:

Chemical and physical stability of the solution after reconstitution has been demonstrated for 12 hours at 25 °C when reconstituted with 0.9 % sodium chloride solution, and for 6 hours at 25 °C when reconstituted with 5 % glucose solution.

From a microbiological standpoint, the product should be used immediately unless reconstitution has been carried out under controlled and aseptic conditions validated by appropriate methods.

Storage conditions.

Store in the original packaging at a temperature not exceeding 25 °C.

Keep out of the reach of children.

Incompatibilities. This medicinal product should not be mixed with other solvents except those specified in the section “Dosage and administration”.

Packaging.

The medicinal product is placed in vials made of amber glass, stoppered with a rubber plug and sealed with an aluminum crimp cap fitted with a flip-off cap ensuring tamper evidence.

1 vial per cardboard box.

Prescription status. Prescription only.

Manufacturer.

Naprod Life Sciences Pvt. Ltd.

NAPROD LIFE SCIENCES Pvt. Ltd.

Manufacturer’s address and location of manufacturing site.

G-17/1, M.I.D.C., Tarapur, Boisar, Dist-Thane 401 506, Maharashtra State, India

Marketing authorization holder.

M.Biotech Ltd

Address of marketing authorization holder.

Gladstone House, 77-79 High Street, Egham TW20 9HY, Surrey, United Kingdom