Losec M Prilosec [Rx Classification Agent to suppress gastric acid secretion

Action/Kinetics: Thought to be a gastric pump inhibitor in that it blocks the final step of acid production by inhibiting the H+—K+ proton ATPase system at the secretory surface of the gastric parietal cell. Both basal and stimulated acid secretions are inhibited. Serum gastrin levels are increased during the first 1 or 2 weeks of therapy and are maintained at such levels during the course of therapy. Because omepra-zole is acid-labile, the product contains an enteric-coated granule formulation; however, absorption is rapid. Peak plasma levels: 0.5-35 hr. Onset: Within 1 hr. tVi: 0.5-1 hr. Duration: Up to 72 hr (due to prolonged binding of the drug to the parietal H+-K+; ATPase enzyme). Significantly bound (95%) to plasma protein. Metabolized in the liver and inactive metabolites are excreted through the urine. Consider dosage adjustment in Asians. Uses: Short-term (4- to 8-week) treatment of active duodenal ulcer, active benign gastric ulcer, erosive esophagitis (all grades), and heartburn and other symptoms associated with GERD. In combination with clarithromycin for eradication of Helicobacter pylori and active duodenal ulcer. Long-term maintenance therapy for healed erosive esophagitis. Long-term treatment of pathologic hypersecretory conditions such as Zollinger-Ellison syndrome, multiple endocrine adenomas, and systemic mastocytosis. Non-FDA Approved Uses: In combination with amoxicillin for eradication of H. pylori. Contraindications: Lactation. Use as maintenance therapy for duodenal ulcer disease.

Special Concerns: Bioavailability may be increased in geriatric clients. Use with caution during lactation. Symptomatic effects with omepra-zole do not preclude gastric malignan cy. Safety and effectiveness have not been determined in children. Side Effects: CNS: Headache, dizziness. Possibly, anxiety disorders, abnormal dreams, vertigo, insomnia, nervousness, apathy, paresthesia, somnolence, depression, aggression, hallucinations, hemifacial dysesthe-sia, tremors, confusion. Oral: Dry mouth, mucosal atrophy of the tongue, taste perversion, candidiasis. GI: Diarrhea, N&V, abdominal pain, abdominal swellling, constipation, flatulence, anorexia, fecal discoloration, esophageal candidiasis, irritable colon, gastric fundic gland polyps, gastroduodenal carcinoids. Hepatic: Pancreatitis. Overt liver disease, including hepatocellular, choles-tatic, or mixed hepatitis; liver necrosis, hepatic failure, hepatic encephalopathy. CV: Angina, chest pain, tachycardia, bradycardia, palpitation, peripheral edema, elevated BP. Respiratory: Upper respiratory infection, pharyngeal pain, bronchospasms, cough, epistaxis. Dermatologic: Rash, severe generalized skin reaction including toxic epidermal necrolysis, Stevens-Johnson syndrome; erythema multiforme, skin inflammation, urticaria, pruritus, alopecia, dry skin, hyperhidrosis. GU: UTI, acute interstitial nephritis, urinary frequency, hematuria, proteinuria, glycosuria, testicular pain, microscopic pyuria, gynecomastia. Hematologic: Pancy-topenia, thrombocytopenia, anemia, leukocytosis, neutropenia, hemolytic anemia, agranulocytosis. Musculoskeletal: Asthenia, back pain, myalgia, joint pain, muscle cramps, muscle weakness, leg pain. Miscellaneous: Rash, angioedema, fever, pain, gout, fatigue, malaise, weight gain, tinnitus, alteration in taste.

When used with clarithromycin the following additional side effects were noted: Tongue discoloration, rhinitis, pharyngitis, and flu syndrome.

NOTE: Data are lacking on the effect of long-term hypochlorhydria and hypergastrinemia on the risk of developing tumors.

Drug Interactions

Ampicillin (esters) / Possible l absorption of ampicillin esters due to T pH of stomach

Diazepam / T Plasma levels of diazepam due to l rate of metabolism by the liver

Ketoconazole / Possible l absorption of ketoconazole due to T pH of stomach

Phenytoin / T Plasma levels of phenytoin due to l rate of metabolism of the liver

How Supplied: Enteric coated capsule: 10 mg, 20 mg

Dosage-

• Capsules, Eneric-Coated

Active duodenal ulcer. Adults, 20 mg/day for 4-8 weeks.

Erosive esophagitis, heartburn, symptoms associated with GERD. Adults: 20 mg/day for 4-8 weeks. Maintenance of healing erosive esophagitis: 20 mg daily.

Treatment of H. pylori, reduction of risk of duodenal ulcer recurrence. Days 1—14: Omeprazole, 40 mg dai-

■ ly in the morning, plus clarithromycin, 0 500 mg t.i.d. Days 15-28: Omepra-zole, 20 mg daily.

Pathologic hypersecretory conditions.

Adults, initial: 60 mg/day; then, dose individualized although doses up to 120 mg t.i.d. have been used. Daily doses > 80 mg should be divided.

Gastric ulcers. Adults: 40 mg once daily for 4-8 weeks.

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