Omeprazole
Omeprazole (Losec , Prilosec)
Omeprazole
(oh- MEH-prah-zohl)
Pregnancy Category: C Losec 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 ⁺ 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 omeprazole is acid-labile, the product contains an enteric-coated granule formulation; however, absorption is rapid. Peak plasma levels: 0.5-3.5 hr. Onset: Within 1 hr. t 1/2: 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 treatment of active duodenal ulcer. In combination with clarithromycin and amoxicillin for eradication of H. pylori and treatment of 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. Investigational: Posterior laryngitis, enhanced efficacy of pancreatin for treating steatorrhea in cystic fibrosis.

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 omeprazole do not preclude gastric malignancy. 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 dysesthesia, tremors, confusion. GI: Diarrhea, N&V, abdominal pain, abdominal swellling, constipation, flatulence, anorexia, fecal discoloration, esophageal candidiasis, mucosal atrophy of the tongue, dry mouth, irritable colon, gastric fundic gland polyps, gastroduodenal carcinoids. Hepatic: Pancreatitis. Overt liver disease, including hepatocellular, cholestatic, or mixed hepatitis; liver necrosis, hepatic failure hepatic encephalopathy. CV: Angina, chest pain, tachycardia, bradycardia, palpitation, peripheral edema, elevated BP. Respiratory: URI, 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: Pancytopenia, 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.

Laboratory Test Alterations: AST, ALT, gamma-glutamyl transpeptidase, alkaline phosphatase, bilirubin, serum creatinine. Glycosuria, hyponatremia, hypoglycemia.

Overdose Management: Symptoms: Confusion, drowsiness, blurred vision, tachycardia, nausea, diaphoresis, flushing, headache, dry mouth. Treatment: Symptomatic and supportive. Omeprazole is not readily dialyzable.

Drug Interactions: Ampicillin (esters) / Possible absorption of ampicillin esters R/T stomach pH Clarithromycin / Possible plasma levels of both drugs Diazepam / Diazepam plasma levels R/T rate of liver metabolism Iron salts / Possible absorption of iron salts R/T stomach pH Ketoconazole / Possible ketoconazole absorption R/T stomach pH Phenytoin / Plasma phenytoin levels R/T rate of liver metabolism Sucralfate / Omeprazole absorption; take 30 min before sucralfate Warfarin / Prolonged rate of warfarin elimination R/T rate of liver metabolism

How Supplied: Enteric Coated Capsule: 10 mg, 20 mg, 40 mg

Dosage
?Capsules, Enteric-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.
The following regimens may be used: (1) Clarithromycin, 500 mg b.i.d.; amoxicillin, 1 g b.i.d.; and either omeprazole, 20 mg b.i.d. or lansoprazole, 30 mg b.i.d. Each drug is given for 10 days. (2) Clarithromycin, 500 mg b.i.d.; metronidazole, 500 mg b.i.d.; and either omepreazole, 20 mg b.i.d., or lansoprazole, 30 mg b.i.d. Each drug is given for 14 days. (3) Tetracycline, 500 mg q.i.d.; metronidazole, 500 mg q.i.d., bismuth subsalicylate, 525 mg q.i.d.; and either omeprazole, 20 mg/day, or lansoprazole, 30 mg/day. Each drug is given for 14 days.
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 greater than 80 mg should be divided.
Gastric ulcers.
Adults: 40 mg once daily for 4-8 weeks.