Gasec gastro-resistant capsules are indicated for:

Adults • Treatment of duodenal ulcers • Prevention of relapse of duodenal ulcers • Treatment of gastric ulcers • Prevention of relapse of gastric ulcers • In combination with appropriate antibiotics, Helicobacter pylori (H. pylori) eradication in peptic ulcer disease • Treatment of NSAID-associated gastric and duodenal ulcers • Prevention of NSAID-associated gastric and duodenal ulcers in patients at risk • Treatment of reflux esophagitis • Long-term management of patients with healed reflux esophagitis • Treatment of symptomatic gastro-esophageal reflux disease • Treatment of Zollinger-Ellison syndrome

Paediatric use Children over 1 year of age and ≥10 kg • Treatment of reflux esophagitis • Symptomatic treatment of heartburn and acid regurgitation in gastro-esophageal reflux disease

Children and adolescents over 4 years of age • In combination with antibiotics in treatment of duodenal ulcer caused by H. pylori

Posology in adults Treatment of duodenal ulcers The recommended dose in patients with an active duodenal ulcer is Gasec 20 mg once daily. In most patients healing occurs within two weeks. For those patients who may not be fully healed after the initial course, healing usually occurs during a further two weeks treatment period. In patients with poorly responsive duodenal ulcer Gasec 40 mg once daily is recommended and healing is usually achieved within four weeks.

Prevention of relapse of duodenal ulcers For the prevention of relapse of duodenal ulcer in H. pylori negative patients or when H. pylori eradication is not possible the recommended dose is Gasec 20 mg once daily. In some patients a daily dose of 10 mg may be sufficient. In case of therapy failure, the dose can be increased to 40 mg.

Treatment of gastric ulcers The recommended dose is Gasec 20 mg once daily. In most patients healing occurs within four weeks. For those patients who may not be fully healed after the initial course, healing usually occurs during a further four weeks treatment period. In patients with poorly responsive gastric ulcer Gasec 40 mg once daily is recommended and healing is usually achieved within eight weeks.

Prevention of relapse of gastric ulcers For the prevention of relapse in patients with poorly responsive gastric ulcer the recommended dose is Gasec 20 mg once daily. If needed the dose can be increased to Gasec 40 mg once daily.

H. pylori eradication in peptic ulcer disease For the eradication of H. pylori the selection of antibiotics should tolerance, and should be undertaken in accordance with national, regional and local resistance patterns and treatment guidelines.

• Gasec 20 mg + clarithromycin 500 mg + amoxicillin 1,000 mg, each twice daily for one week, or

• Gasec 20 mg + clarithromycin 250 mg (alternatively 500 mg) + metronidazole 400 mg (or 500 mg or tinidazole 500 mg), each twice daily for one week, or • Gasec 40 mg once daily with amoxicillin 500 mg and metronidazole 400 mg (or 500 mg or tinidazole 500 mg), both three times a day for one week.

In each regimen, if the patient is still H. pylori positive, therapy may be repeated.

Treatment of NSAID-associated gastric and duodenal ulcers For the treatment of NSAID-associated gastric and duodenal ulcers, the recommended dose is Gasec 20 mg once daily. In most patients healing occurs within four weeks. For those patients who may not be fully healed after the initial course, healing usually occurs during a further four weeks treatment period.

Prevention of NSAID-associated gastric and duodenal ulcers in patients at risk For the prevention of NSAID associated gastric ulcers or duodenal ulcers in patients at risk (age> 60, previous history of gastric and duodenal ulcers, previous history of upper GI bleeding) the recommended dose is Gasec 20 mg once daily.

Treatment of reflux esophagitis The recommended dose is Gasec 20 mg once daily. In most patients healing occurs within four weeks. For those patients who may not be fully healed after the initial course, healing usually occurs during a further four weeks treatment period. In patients with severe esophagitis Gasec 40 mg once daily is recommended and healing is usually achieved within eight weeks.

Long-term management of patients with healed reflux esophagitis For the long-term management of patients with healed reflux esophagitis the recommended dose is Gasec 10 mg once daily. If needed, the dose can be increased to Gasec 20-40 mg once daily.

Treatment of symptomatic gastro-esophageal reflux disease The recommended dose is Gasec 20 mg daily. Patients may respond adequately to 10 mg daily, and therefore individual dose adjustment should be considered. Continuously treatment in 2-3 days may be required in order to get relief of symptom. Most patients get full relief of the heartburn within 7 days. When full relief of symptom is attained the treatment should be discontinued. If symptom control has not been achieved after 4 weeks treatment with Gasec 20 mg daily, further investigation is recommended.

Treatment of Zollinger-Ellison syndrome In patients with Zollinger-Ellison syndrome the dose should be individually adjusted and treatment continued as long as clinically indicated. The recommended initial dose is Gasec 60 mg daily. All patients with severe disease and inadequate response to other therapies have been effectively controlled and more than 90% of the patients maintained on doses of Gasec 20–120 mg daily. When dose exceed Gasec 80 mg daily, the dose should be divided and given twice daily.

Posology in children

Children over 1 year of age and ≥10 kg Treatment of reflux esophagitis

Symptomatic treatment of heartburn and acid regurgitation in gastro-esophageal reflux disease

The posology recommendations are as follows:

Age Weight Posology ≥1 year of age 10-20 kg 10 mg once daily. The dose can be increased to 20 mg once daily if needed ≥2 years of age > 20 kg 20 mg once daily. The dose can be increased to 40 mg once daily if needed

Reflux esophagitis: The treatment time is 4–8 weeks.

Symptomatic treatment of heartburn and acid regurgitation in gastro-esophageal reflux disease: The treatment time is 2–4 weeks. If symptom control has not been achieved after 2–4 weeks the patient should be investigated further.

 Children and adolescents over 4 years of age  Treatment of duodenal ulcer caused by H. pylori When selecting appropriate combination therapy, consideration should be given to official national, regional and local guidance regarding bacterial resistance, duration of treatment (most commonly 7 days but sometimes up to 14 days), and appropriate use of antibacterial agents.

The treatment should be supervised by a specialist.

The posology recommendations are as follows:

Weight Posology 15-30 kg Combination with two antibiotics: Gasec 10 mg, amoxicillin 25 mg/kg body weight and clarithromycin 7.5 mg/kg body weight are all administrated together two times daily for one week 31-40 kg Combination with two antibiotics: Gasec 20 mg, amoxicillin 750 mg and clarithromycin 7.5 mg/kg body weight are all administrated two times daily for one week > 40 kg Combination with two antibiotics: Gasec 20 mg, amoxicillin 1 g and clarithromycin 500 mg are all administrated two times daily for one week.

Special populations Impaired renal function Dose adjustment is not needed in patients with impaired renal function (see section 5.2).

Impaired hepatic function In patients with impaired hepatic function a daily dose of 10–20 mg may be sufficient (see section 5.2).

Elderly (> 65 years old) Dose adjustment is not needed in the elderly (see section 5.2).

Method of administration It is recommended to take Gasec capsules in the morning, swallowed whole with half a glass of water. The capsules must not be chewed or crushed.

In the presence of any alarm symptom (e.g. significant unintentional weight loss, recurrent vomiting, dysphagia, haematemesis or melena) and when gastric ulcer is suspected or present, malignancy should be excluded, as treatment may alleviate symptoms and delay diagnosis.

Co-administration of atazanavir with proton pump inhibitors is not recommended (see section 4.5). If the combination of atazanavir with a proton pump inhibitor is judged unavoidable, close clinical monitoring (e.g. virus load) is recommended in combination with an increase in the dose of atazanavir to 400 mg with 100 mg of ritonavir; omeprazole 20 mg should not be exceeded.

Omeprazole, as all acid-blocking medicines, may reduce the absorption of vitamin B12 (cyanocobalamin) due to hypo- or achlorhydria. This should be considered in patients with reduced body stores or risk factors for reduced vitamin B12 absorption on long-term therapy.

Omeprazole is a CYP2C19 inhibitor. When starting or ending treatment with omeprazole, the potential for interactions with drugs metabolised through CYP2C19 should be considered. An interaction is observed between clopidogrel and omeprazole (see section 4.5). The clinical relevance of this interaction is uncertain. As a precaution, concomitant use of omeprazole and clopidogrel should be discouraged.

Severe hypomagnesaemia has been reported in patients treated with proton pump inhibitors (PPIs) like omeprazole for at least three months, and in most cases for a year. Serious manifestations of hypomagnesaemia such as fatigue, tetany, delirium, convulsions, dizziness and ventricular arrhythmia can occur but they may begin insidiously and be overlooked. In most affected patients, hypomagnesaemia improved after magnesium replacement and discontinuation of the PPI. For patients expected to be on prolonged treatment or who take PPIs with digoxin or drugs that may cause hypomagnesaemia (e.g. diuretics), healthcare professionals should consider measuring magnesium levels before starting PPI treatment and periodically during treatment.

Proton pump inhibitors, especially if used in high doses and over long durations (>1 year), may modestly increase the risk of hip, wrist and spine fracture, predominantly in the elderly or in presence of other recognized risk factors. Observational studies suggest that proton pump inhibitors may increase the overall risk of fracture by 10-40%. Some of this increase may be due to other risk factors. Patients at risk of osteoporosis should receive care according to current clinical guidelines and they should have an adequate intake of vitamin D and calcium.

Interference with laboratory tests Increased CgA level may interfere with investigations for neuroendocrine tumours. To avoid this interference the omeprazole treatment should be temporarily stopped five days before CgA measurements.

Some children with chronic illnesses may require long-term treatment although it is not recommended.

Gasec gastro-resistant capsules contain sucrose. Patients with rare hereditary problems of fructose intolerance, glucose-galactose malabsorption or sucrase-isomaltase insufficiency should not take this medicine.

 Treatment with proton pump inhibitors may lead to slightly increased risk of gastrointestinal infections such as Salmonella and Campylobacter (see section 5.1).

 As in all long-term treatments, especially when exceeding a treatment period of 1 year, patients should be kept under regular surveillance.

Patients with long-term recurrent symptoms of indigestion or heartburn should see their doctor at regular intervals. Especially, patients over 55 years taking-the-couanter’y‘over-prescription) (OTC, non indigestion or heartburn remedy on a daily basis should inform their pharmacist or doctor.

Subacute cutaneous lupus erythematosus (SCLE): Proton pump inhibitors are associated with very infrequent cases of SCLE. If lesions occur, especially in sun-exposed areas of the skin, and if accompanied by arthralgia, the patient should seek medical help promptly and the health care professional should consider stopping this medication. SCLE after previous treatment with a proton pump inhibitor may increase the risk of SCLE with other proton pump inhibitors.

Patients should be instructed to consult a doctor if:

• They have had previous gastric ulcer or gastrointestinal surgery • They are on continuous symptomatic treatment of indigestion or heartburn for 4 or more weeks • They have jaundice or severe liver disease. • They are aged over 55 years with new or recently changed symptoms.

Patients should not take omeprazole as a preventative medication.

Effects of omeprazole on the pharmacokinetics of other active substances

Active substances with pH dependent absorption The decreased intragastric acidity during treatment with omeprazole might increase or decrease the absorption of active substances with a gastric pH dependent absorption.

Nelfinavir, atazanavir The plasma levels of nelfinavir and atazanavir are decreased in case of co-administration with omeprazole.

Concomitant administration of omeprazole with nelfinavir is contraindicated (see section 4.3). Co- administration of omeprazole (40 mg once daily) reduced mean nelvinavir exposure by ca. 40% and the mean exposure of the pharmacologically active metabolite M8 was reduced by ca. 75-90%. The interaction may also involve CYP2C19 inhibition.

Concomitant administration of omeprazole with atazanavir is not recommended (see section 4.4). Concomitant administration of omeprazole (40 mg once daily) and atazanavir 300 mg/ritonavir 100 mg to healthy volunteers resulted in a 75% decrease of the atazanavir exposure. Increasing the atazanavir

dose to 400 mg did not compensate for the impact of omeprazole on atazanavir exposure. The co- administration of omeprazole (20 mg once daily) with atazanavir 400 mg/ritonavir 100 mg to healthy volunteers resulted in a decrease of approximately 30% in the atazanavir exposure as compared to atazanavir 300 mg/ritonavir 100 mg once daily.

Digoxin Concomitant treatment with omeprazole (20 mg daily) and digoxin in healthy subjects increased the bioavailability of digoxin by 10%. Digoxin toxicity has been rarely reported. However caution should be exercised when omeprazole is given at high doses in elderly patients. Therapeutic drug monitoring of digoxin should be then be reinforced.

Clopidogrel In a crossover clinical study, clopidogrel (300 mg loading dose followed by 75 mg/day) alone and with omeprazole (80 mg at the same time as clopidogrel) were administered for 5 days. The exposure to the active metabolite of clopidogrel was decreased by 46% (Day 1) and 42% (Day 5) when clopidogrel and omeprazole were administered together. Mean inhibition of platelet aggregation (IPA) was diminished by 47% (24 hours) and 30% (Day 5) when clopidogrel and omeprazole were administered together. In another study it was shown that administering clopidogrel and omeprazole at different times did not prevent their interaction that is likely to be driven by the inhibitory effect of omeprazole on CYP2C19. Inconsistent data on the clinical implications of this PK/PD interaction in terms of major cardiovascular events have been reported from observational and clinical studies.

Other active substances The absorption of posaconazole, erlotinib, ketoconazole and itraconazole is significantly reduced and thus clinical efficacy may be impaired. For posaconazole and erlotinib concomitant use should be avoided.

Active substances metabolised by CYP2C19 Omeprazole is a moderate inhibitor of CYP2C19, the major omeprazole metabolising enzyme. Thus, the metabolism of concomitant active substances also metabolised by CYP2C19, may be decreased and the systemic exposure to these substances increased. Examples of such drugs are R-warfarin and other vitamin K antagonists, cilostazol, diazepam and phenytoin.

Cilostazol Omeprazole, given in doses of 40 mg to healthy subjects in a cross-over study, increased Cmax and AUC for cilostazol by 18% and 26% respectively, and one of its active metabolites by 29% and 69% respectively.

Phenytoin Monitoring phenytoin plasma concentration is recommended during the first two weeks after initiating omeprazole treatment and, if a phenytoin dose adjustment is made, monitoring and a further dose adjustment should occur upon ending omeprazole treatment.

Unknown mechanism

Saquinavir Concomitant administration of omeprazole with saquinavir/ritonavir resulted in increased plasma levels up to approximately 70% for saquinavir associated with good tolerability in HIV-infected patients.

Tacrolimus Concomitant administration of omeprazole has been reported to increase the serum levels of tacrolimus.  A reinforced monitoring of tacrolimus concentrations as well as renal function (creatinine clearance) should be performed, and dosage of tacrolimus adjusted if needed.

Methotrexate When given together with proton pump inhibitors, methotrexate levels have been reported to increase in some patients. In high-dose methotrexate administration a temporary withdrawal of omeprazole may need to be considered.

Effects of other active substances on the pharmacokinetics of omeprazole

Inhibitors of CYP2C19 and/or CYP3A4 Since omeprazole is metabolised by CYP2C19 and CYP3A4, active substances known to inhibit CYP2C19 or CYP3A4 (such as clarithromycin and voriconazole) may lead to increased omeprazole serum levels by decreasing of metabolism omeprazole’s. Concomitant voriconazole treatment rate resulted in more than doubling of the omeprazole exposure. As high doses of omeprazole have been well-tolerated adjustment of the omeprazole dose is not generally required. However, dose adjustment should be considered in patients with severe hepatic impairment and if long-term treatment is indicated.

Inducers of CYP2C19 and/or CYP3A4 Active substances known to induce CYP2C19 or CYP3A4 or both may lead to decreased omeprazole serum levels by increasing omeprazole's rate of metabolism.

 Results from three prospective epidemiological studies (more than 1000 exposed outcomes) indicate no adverse effects of omeprazole on pregnancy or on the health of the foetus/newborn child. Omeprazole can be used during pregnancy.

 Omeprazole is excreted in breast milk but is not likely to influence the child when therapeutic doses are used.

Gasec is not likely to affect the ability to drive or use machines. Adverse drug reactions such as dizziness and visual disturbances may occur (see section 4.8). If affected, patients should not drive or operate machinery. 

The most common side effects (1-10% of patients) are headache, abdominal pain, constipation, diarrhoea, flatulence and nausea/vomiting.

The following adverse drug reactions have been identified or suspected in the clinical trials programme for omeprazole and post-marketing. None was found to be dose-

related. Adverse reactions listed below are classified according to frequency and System Organ Class (SOC). Frequency categories are defined according to the following very common (> 1/10); common (> 1/100 and < 1/10); uncommon (> 1/1,000 and < 1/100); rare (> 1/10,000 and < 1/1,000); very rare (< 1/10,000), not known (cannot be estimated from the available data). SOC/frequency Adverse reaction

Blood and lymphatic system disorders Rare: Leukopenia, thrombocytopenia Very rare: Agranulocytosis, pancytopenia Immune system disorders Rare: Hypersensitivity reactions e.g. fever, angioedema and anaphylactic reaction/shock

Metabolism and nutrition disorders Rare: Hyponatraemia Not known: Hypomagnesaemia Psychiatric disorders Uncommon: Insomnia Rare: Agitation, confusion, depression Very rare: Aggression, hallucinations Nervous system disorders Common: Headache Uncommon: Dizziness, paraesthesia, somnolence Rare: Taste disturbance Eye disorders  Rare: Blurred vision Ear and labyrinth disorders Uncommon: Vertigo Respiratory, thoracic and mediastinal disorders Rare: Bronchospasm Gastrointestinal disorders Common: Abdominal pain, constipation, diarrhoea, flatulence, nausea/vomiting Rare: Dry mouth, stomatitis, gastrointestinal candidiasis Not known: Microscopic colitis Hepatobiliary disorders Uncommon: Increased liver enzymes Rare: Hepatitis with or without jaundice Very rare: Hepatic failure, encephalopathy in patients with pre-existing liver disease Skin and subcutaneous tissue disorders Uncommon: Dermatitis, pruritus, rash, urticaria Rare: Alopecia, photosensitivity Very rare: Erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis  (TEN) Musculoskeletal and connective tissue disorders Uncommon Fracture of the hip, wrist or spine

Rare: Arthralgia, myalgia Very rare: Muscular weakness Renal and urinary disorders Rare: Interstitial nephritis Reproductive system and breast disorders Very rare: Gynaecomastia General disorders and administration site conditions Uncommon: Malaise, peripheral oedema Rare: Increased sweating

Paediatric population The safety of omeprazole has been assessed in a total of 310 children aged 0 to 16 years with acid-related disease. There are limited long term safety data from 46 children who received maintenance therapy of omeprazole during a clinical study for severe erosive esophagitis for up to 749 days. The adverse event profile was generally the same as for adults in short- as well as in long-term treatment. There are no long term data regarding the effects of omeprazole treatment on puberty and growth.

To report any side effect(s):

• Saudi Arabia:

-The National Pharmacovigilance and Drug Safety Centre (NPC) o Fax: +966-11-205-7662 o Call NPC at +966-11-2038222, Exts: 2317-2356-2353-2354-2334-2340. o Toll free phone: 8002490000 o E-mail: npc.drug@sfda.gov.sa o Website: www.sfda.gov.sa/npc.

There is limited information available on the effects of overdoses of omeprazole in humans. In the literature, doses of up to 560 mg have been described, and occasional reports have been received when single oral doses have reached up to 2,400 mg omeprazole (120 times the usual recommended clinical dose). Nausea, vomiting, dizziness, abdominal pain, diarrhoea and headache have been reported. Also apathy, depression and confusion have been described in single cases.

The symptoms described in connection to omeprazole overdose have been transient, and no serious outcome has been reported. The rate of elimination was unchanged (first order kinetics) with increased doses. Treatment, if needed, is symptomatic.

Pharmacotherapeutic group: Proton pump inhibitors, ATC code: A02BC01

Mechanism of action Omeprazole, a racemic mixture of two enantiomers reduces gastric acid secretion through a highly targeted mechanism of action. It is a specific inhibitor of the acid pump in the parietal cell. It is rapidly acting and provides control through reversible inhibition of gastric acid secretion with once daily dosing.

 Omeprazole is a weak base and is concentrated and converted to the active form in the highly acidic environment of the intracellular canaliculi within the parietal cell, where it inhibits the enzyme H+ K+- ATPase - the acid pump. This effect on the final step of the gastric acid formation process is dose- dependent and provides for highly effective inhibition of both basal acid secretion and stimulated acid secretion, irrespective of stimulus.

Pharmacodynamic effects All pharmacodynamic effects observed can be explained by the effect of omeprazole on acid secretion.

Effect on gastric acid secretion Oral dosing with omeprazole once daily provides for rapid and effective inhibition of daytime and night-time gastric acid secretion with maximum effect being achieved within 4 days of treatment. With omeprazole 20 mg, a mean decrease of at least 80% in 24-hour intragastric acidity is then maintained in duodenal ulcer patients, with the mean decrease in peak acid output after pentagastrin stimulation being about 70% 24 hours after dosing.

Oral dosing with omeprazole 20 mg maintains an intragastric pH of ≥3 for a mean time of 17 hours of the 24-hour period in duodenal ulcer patients.

As a consequence of reduced acid secretion and intragastric acidity, omeprazole dose-dependently reduces/normalizes acid exposure of the esophagus in patients with gastro-esophageal reflux disease. The inhibition of acid secretion is related to the area under the plasma concentration-time curve (AUC) of omeprazole and not to the actual plasma concentration at a given time.

No tachyphylaxis has been observed during treatment with omeprazole.

Effect on H. pylori H. pylori is associated with peptic ulcer disease, including duodenal and gastric ulcer disease. H. pylori is a major factor in the development of gastritis. H. pylori together with gastric acid are major factors in the development of peptic ulcer disease. H. pylori is a major factor in the development of atrophic gastritis which is associated with an increased risk of developing gastric cancer.

 Eradication of H. pylori with omeprazole and antimicrobials is associated with high rates of healing and long-term remission of peptic ulcers

Dual therapies have been tested and found to be less effective than triple therapies. They could, however, be considered in cases where known hypersensitivity precludes use of any triple combination.

Other effects related to acid inhibition During long-term treatment gastric glandular cysts have been reported in a somewhat increased frequency. These changes are a physiological consequence of pronounced inhibition of acid secretion, are benign and appear to be reversible.

Decreased gastric acidity due to any means including proton pump inhibitors, increases gastric counts of bacteria normally present in the gastrointestinal tract. Treatment with acid-reducing drugs may lead to slightly increased risk of gastrointestinal infections such as Salmonella and Campylobacter.

 Chromogranin A (CgA) also increases due to decreased gastric acidity. This CgA modifying effect cannot be demonstrated five days after stopping treatment with PPIs.

Paediatric use In a non-controlled study in children (1 to 16 years of age) with severe reflux esophagitis, omeprazole at doses of 0.7 to 1.4 mg/kg improved esophagitis level in 90% of the cases and significantly reduced reflux symptoms. In a single-blind study, children aged 0–24 months with clinically diagnosed gastro- esophageal reflux disease were treated with 0.5, 1.0 or 1.5 mg omeprazole/kg. The frequency of vomiting/regurgitation episodes decreased by 50% after 8 weeks of treatment irrespective of the dose.

Eradication of H. pylori in children A randomised, double blind clinical study (Héliot study) concluded that omeprazole, in combination with two antibiotics (amoxicillin and clarithromycin), was safe and effective in the treatment of H. pylori infection in children age 4 years old and above with gastritis: H. pylori eradication rate: 74.2% (23/31 patients) with omeprazole + amoxicillin + clarithromycin versus 9.4% (3/32 patients) with amoxicillin + clarithromycin. However, there was no evidence of any clinical benefit with respect to dyspeptic symptoms. This study does not support any information for children aged less than 4 years.

Absorption Omeprazole and omeprazole magnesium are acid labile and are therefore administered orally as enteric-coated granules in capsules or capsules. Absorption of omeprazole is rapid, with peak plasma levels occurring approximately 1-2 hours after dose. Absorption of omeprazole takes place in the small intestine and is usually completed within 3-6 hours. Concomitant intake of food has no influence on the bioavailability. The systemic availability (bioavailability) from a single oral dose of omeprazole is approximately 40%. After repeated once-daily administration, the bioavailability increases to about 60%.

Distribution The apparent volume of distribution in healthy subjects is approximately 0.3 l/kg body weight. Omeprazole is 97% plasma protein bound.

Bioequivalence between Gasec capsules and Gasec gastro-resistant capsules, based on both area under the omeprazole plasma concentration-time curve (AUC) and maximum plasma concentration (Cmax) of omeprazole, has been demonstrated for all doses, 10 mg, 20 mg and 40 mg.

Metabolism Omeprazole is completely metabolised by the cytochrome P450 system (CYP). The major part of its metabolism is dependent on the polymorphically expressed CYP2C19, responsible for the formation of hydroxyomeprazole, the major metabolite in plasma. The remaining part is dependent on another specific isoform, CYP3A4, responsible for the formation of omeprazole sulphone. As a consequence of high affinity of omeprazole to CYP2C19, there is a potential for competitive inhibition and metabolic drug-drug interactions with other substrates for CYP2C19. However, due to low affinity to CYP3A4, omeprazole has no potential to inhibit the metabolism of other CYP3A4 substrates. In addition, omeprazole lacks an inhibitory effect on the main CYP enzymes.

Approximately 3% of the Caucasian population and 15-20% of Asian populations lack a functional CYP2C19 enzyme and are called poor metabolisers. In such individuals the metabolism of omeprazole is probably mainly catalysed by CYP3A4. After repeated once-daily administration of 20 mg omeprazole, the mean AUC was 5 to 10 times higher in poor metabolisers than in subjects having a functional CYP2C19 enzyme (extensive metabolisers). Mean peak plasma concentrations were also higher, by 3 to 5 times. These findings have no implications for the posology of omeprazole.

Excretion The plasma elimination half-life of omeprazole is usually shorter than one hour both after single and repeated oral once-daily dosing. Omeprazole is completely eliminated from plasma between doses with no tendency for accumulation during once-daily administration. Almost 80% of an oral dose of omeprazole is excreted as metabolites in the urine, the remainder in the faeces, primarily originating from bile secretion.

The AUC of omeprazole increases with repeated administration. This increase is dose-dependent and results in a non-linear dose-AUC relationship after repeated administration. This time- and dose-dependency is due to a decrease of first pass metabolism and systemic clearance probably caused by an inhibition of the CYP2C19 enzyme by omeprazole and/or its metabolites (e.g. the sulphone). No metabolite has been found to have any effect on gastric acid secretion.

Special populations

Impaired hepatic function The metabolism of omeprazole in patients with liver dysfunction is impaired, resulting in an increased AUC. Omeprazole has not shown any tendency to accumulate with once-daily dosing.

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

Elderly The metabolism rate of omeprazole is somewhat reduced in elderly subjects (75-79 years of age).

Paediatric patients During treatment with the recommended doses to children from the age of 1 year, similar plasma concentrations were obtained as compared to adults. In children younger than 6 months, clearance of omeprazole is low due to low capacity to metabolise omeprazole.

Gastric ECL-cell hyperplasia and carcinoids, have been observed in life-long studies in rats treated with omeprazole. These changes are the result of sustained hypergastrinaemia secondary to acid inhibition. Similar findings have been made after treatment with H2-receptor antagonists, proton pump inhibitors and after partial fundectomy. Thus, these changes are not from a direct effect of any individual active substance.

- Gastro - resistant pellets: Sugar sphere, hydroxypropyl methylcellulose, disodium hydrogen phosphate, Syloid 244, titanium dioxide (E 171), Eudragit L30 D, Citroflex 2, talc. - Capsule composition: Gelatine, titanium dioxide (E 171), iron oxide (E 172), indigotine (E 132).

Not applicable.

Keep out of the reach and sight of children.  

Do not store above 30 ºC. Keep the bottle tightly closed in order to protect from moisture.

Use within 4 weeks after opening.

White bottle of high density polyethylene (HDPE) with cap and desiccant.

Gasec - 10: Packs of 14 and 28 Gastrocaps.

Gasec - 20: Packs of 7, 14, 28 and 56 Gastrocaps.

Gasec - 40: Packs of 14 and 28 Gastrocaps.

Not all pack sizes may be marketed.

No special requirements.