Omeprazole is an antiulcer drug, an inhibitor of the H + / K + adenosine triphosphate (ATP) phase. It inhibits the activity of H + / K + - adenosine triphosphate (ATP phases (H + / K + adenosine triphosphate (ATP) phases, it is also a ""proton pump"" or ""proton pump"") in the parietal cells of the stomach, thereby blocking ion transfer hydrogen and the final stage of the synthesis of hydrochloric acid in the stomach.
Omeprazole is a prodrug. In the acidic environment of the tubules of parietal cells, omeprazole is converted into the active metabolite sulfenamide, which inhibits the membrane H + / K + - adenosine triphosphate (ATP) phase, connecting with it due to the disulfide bridge. This explains the high selectivity of the action of omeprazole specifically on parietal cells, where there is a medium for the formation of sulfenamide. Biotransformation of omeprazole to sulfenamide occurs rapidly (after 2-4 minutes). Sulfenamide is a cation and is not absorbed.
Omeprazole suppresses the basal and secretion of hydrochloric acid stimulated by any stimulus at the final stage. It reduces the total volume of gastric secretion and inhibits the release of pepsin. Gastroprotective activity was detected in omeprazole, the mechanism of which is not clear. Does not affect the production of Castle's internal factor and the rate of transition of the food mass from the stomach to the duodenum. Omeprazole does not act on acetylcholine and histamine receptors.
Omeprazole capsules contain coated microgranules, the gradual release and onset of action of omeprazole begins 1 hour after administration, reaches a maximum after 2 hours, lasts for 24 hours or more. Inhibition of 50% of maximum secretion after a single dose of 20 mg of the drug lasts 24 hours.
A single dose per day provides quick and effective inhibition of day and night gastric secretion, reaching its maximum after 4 days of treatment. In patients with peptic ulcer of the duodenum, taking 20 mg of omeprazole maintains pH = 3 inside the stomach for 17 hours. After stopping the drug, secretory activity is fully restored after 3-5 days.
Absorption is high. Bioavailability of 30-40% (with liver failure increases to almost 100%), increases in the elderly and in patients with impaired liver function, renal failure has no effect. TCmax - 0.5-3.5 hours.
Possessing high lipophilicity, it easily penetrates into the parietal cells of the stomach. Communication with plasma proteins - 90-95% (albumin and acid alpha1-glycoprotein).
T1 / 2 - 0.5-1 hours (with liver failure - 3 hours), clearance - 500-600 ml / min. It is almost completely metabolized in the liver with the participation of the CYP2C19 enzyme system, with the formation of 6 pharmacologically inactive metabolites (hydroxyomeprazole, sulfide and sulfone derivatives, etc.). It is an inhibitor of the isoenzyme CYP2C19. Excretion by the kidneys (70-80%) and with bile (20-30%) in the form of metabolites.
In chronic renal failure, excretion decreases in proportion to a decrease in creatine clearance. In elderly patients, excretion is reduced.
Precautions: renal and / or liver failure.
Pregnancy and lactation
Contraindicated during pregnancy and lactation.
From the digestive system: diarrhea or constipation, abdominal pain, nausea, vomiting, flatulence; in rare cases - increased activity of liver enzymes, taste disturbances, in some cases - dry mouth, stomatitis, in patients with previous severe liver disease - hepatitis (including jaundice), impaired liver function.
From the nervous system: in patients with severe concomitant somatic diseases - headache, dizziness, agitation, depression, in patients with previous severe liver disease - encephalopathy.
From the musculoskeletal system: in some cases - arthralgia, myasthenia gravis, myalgia.
From the hemopoietic system: in some cases - leukopenia, thrombocytopenia, agranulocytosis, pancytopepia.
From the skin: rarely - a skin rash and / or itching, in some cases photosensitivity, erythema multiforme, alopecia.
Allergic reactions: urticaria, angioedema, fever, bronchospasm, interstitial nephritis and anaphylactic shock.
Other: rarely - visual impairment, malaise, peripheral edema, increased sweating, gynecomastia, the formation of gastric glandular cysts during prolonged treatment (due to inhibition of hydrochloric acid secretion, is benign, reversible).
May decrease the absorption of ampicillin esters, iron salts, itraconazole and ketoconazole (omeprazole increases the pH of the stomach).
Being inhibitors of cytochrome P450, it can increase the concentration and decrease the excretion of diazepam, indirect anticoagulants, phenytoin (drugs that are metabolized in the liver by cytochrome CYP2C19), which in some cases may require a reduction in the doses of these drugs. May increase the concentration of clarithromycin in blood plasma.
At the same time, prolonged use of omeprazole at a dose of 20 mg once a day in combination with caffeine, theophylline, piroxicam, diclofenac, naproxen, metoprolol, propranolol, ethanol, cyclosporine, lidocaine, quinidine, and estradiol did not lead to a change in their plasma concentration.
Enhances the inhibitory effect on the hematopoietic system and other drugs.
No interaction with concomitantly taken antacids was noted.
Dosage and administration
Inside, capsules are usually taken in the morning, without chewing, washed down with a small amount of water (just before meals).
With exacerbation of peptic ulcer, reflux esophagitis and gastropathy caused by taking NSAIDs - 20 mg once a day. In patients with severe reflux esophagitis, the dose is increased to 40 mg once a day. The course of treatment for peptic ulcer of the duodenum is 2-4 weeks, if necessary - 4-5 weeks; with gastric ulcer, with reflux esophagitis, with erosive and ulcerative lesions of the gastrointestinal tract caused by NSAIDs - within 4-8 weeks.
Reducing the symptoms of the disease and scarring of the ulcer in most cases occurs within 2 weeks. Patients who did not have complete ulceration of the ulcer after a two-week course should continue treatment for another 2 weeks.
Patients resistant to treatment with other antiulcer drugs are prescribed 40 mg per day. The course of treatment for peptic ulcer of the duodenum is 4 weeks, for peptic ulcer of the stomach and reflux esophagitis - 8 weeks.
With Zollinger-Elisson syndrome, usually 60 mg once a day; if necessary, increase the dose to 80-120 mg / day (the dose is divided into 2 doses).
For the prevention of relapse of peptic ulcer - 10 mg 1 time per day.
To eradicate Helicobacter pylori, “triple” therapy is used (within 1 week: omeprazole 20 mg, amoxicillin 1 g, clarithromycin 500 mg - 2 times a day; or omeprazole 20 mg, clarithromycin 250 mg, metronidazole 400 mg - 2 times a day day; or omeprazole 40 mg once a day, amoxicillin 500 mg and metronidazole 400 mg - 3 times a day) or “double” therapy (within 2 weeks: omeprazole 20-40 mg and amoxicillin 750 mg - 2 times a day or omeprazole 40 mg - 1 time per day and clarithromycin 500 mg 3 times a day or amoxicillin 0.75-1.5 g -2 times a day).
In case of liver failure, 10-20 mg is prescribed once a day (in severe liver failure, the daily dose should not exceed 20 mg); in case of impaired renal function and in elderly patients, correction of the dosage regimen is not required.
Symptoms: confusion, blurred vision, drowsiness, dry mouth, nausea, tachycardia, arrhythmia, headache.
Treatment: symptomatic. Hemodialysis is not effective enough. There is no specific antidote.
Before starting therapy, it is necessary to exclude the presence of a malignant process (especially with a stomach ulcer), since treatment, masking the symptoms, can delay the correct diagnosis.
Reception at the same time with food does not affect its effectiveness.