Omeprazole

Indications

Omeprazole is used for: Peptic ulcer, H. pylori infection, Gastro-oesophageal reflux disease, Zollinger-Ellison syndrome, Oesophagitis, Acid-related dyspepsia, NSAID-associated ulceration

Adult Dose

Oral Peptic ulcer Adult: 20 or 40 mg/day in severe cases for 4 wk (duodenal ulcer) or for 8 wk (gastric ulcer). Maintenance: 10-20 mg/day. All doses to be taken once in the morning. NSAID-associated ulceration Adult: 20 mg once in the morning. Gastro-oesophageal reflux disease Adult: 20 mg/day for 4 wk may continue for another 4-8 wk if necessary. Refractory oesophagitis: 40 mg/day. Maintenance: 20 mg/day (after healing of oesophagitis); 10 mg/day (acid reflux). All doses to be taken once in the morning. Zollinger-Ellison syndrome Adult: Initially, 60 mg once in the morning, adjust as required. Dose Range: 20-120 mg/day. Doses >80 mg are administered in 2 divided doses. Prophylaxis of acid aspiration during general anaesthesia Adult: 40 mg given in the evening and another 40 mg 2-6 hr pre-op. Acid-related dyspepsia Adult: 10 or 20 mg once in the morning for 2-4 wk. Erosive oesophagitis Adult: 20 mg/day for 4-8 wk. Maintenance of healing: 20 mg/day for up to 12 mth. All doses to be taken once in the morning. H.pylori infection Adult: As triple therapy: 20 mg bid or 40 mg once daily combined w/ amoxicillin 500 mg and metronidazole 400 mg both tid or combined w/ clarithromycin 250 mg and metronidazole 400 mg (or tinidazole 500 mg) both bid or combined w/ amoxicillin 1 g and clarithromycin 500 mg both bid. Duration: 7 or 10 days. As 2-wk dual therapy: 20 mg bid or 40 mg/day combined w/ either amoxicillin 750 mg to 1 g bid or w/ clarithromycin 500 mg tid. Intravenous Gastro-oesophageal reflux disease; Gastric and duodenal ulcers; NSAID-associated ulceration Adult: 40 mg once daily infused over 20-30 min or slow inj over 5 min until oral admin is possible. Zollinger-Ellison syndrome Adult: Initially, 60 mg/day, adjust according to response. Daily doses >60 mg/day should be given in 2 divided doses. Elderly: No dosage adjustment needed. Hepatic impairment: 10-20 mg/day.

Child Dose

Oral GERD Indicated for treatment of GERD <1 year: Safety and efficacy not established > 1 year 5-10 kg: 5 mg PO qDay 10-20 kg: 10 mg PO qDay >20 kg: 20 mg PO qDay Erosive Esophagitis Indicated for treatment and to maintain healing of erosive esophagitis caused by acid-mediated GERD <1 month: Safety and efficacy not established Aged 1 month to <1 year 3 to <5 kg: 2.5 mg qDay 5 to <10 kg: 5 mg qDay >10 kg: 10 mg qDay May treat for up to 6 weeks Aged 1-16 years 5 to <10 kg: 5 mg PO qDay 10 to <20 kg: 10 mg PO qDay >20 kg: 20 mg PO qDay May treat for 4-8 weeks

Renal Dose

Renal impairment: No dosage adjustment needed.

Administration

Delayed-release cap: Should be taken on an empty stomach. Take at least 1 hr before meals. Swallow whole, do not chew/crush. For patients w/ difficulty swallowing, cap may be carefully opened & entire contents sprinkled in a spoonful of applesauce. Swallow drug/food mixt w/o chewing immediately after prep. Drug/food mixt should not be stored for future use. Powd for oral susp: Should be taken on an empty stomach. Take on an empty stomach at least 1 hr before a meal. MUPS tab: May be taken with or without food. Cap: Should be taken with food. Take immediately before a meal.

Contra Indications

Known hypersensitivity to any of its component.

Precautions

Gastric malignancy should be ruled out. Pregnancy, lactation, childn <1 yr. Monitoring Parameters Monitor Mg concentrations prior to initiation and periodically thereafter. Lactation Risk Summary Limited data suggest omeprazole may be present in human milk; there are no clinical data on effects of omeprazole on breastfed infant or on milk production; developmental and health benefits of breastfeeding should be considered along with mother's clinical need for therapy and any potential adverse effects on breastfed infant from treatment or from underlying maternal condition

Pregnancy-Lactation

Risk Summary There are no adequate and well-controlled studies with Omeprazole in pregnant women. Available epidemiologic data fail to demonstrate an increased risk of major congenital malformations or other adverse pregnancy outcomes with first trimester omeprazole use. Reproduction studies in rats and rabbits resulted in dose-dependent embryo-lethality at omeprazole doses that were approximately 3.4 to 34 times an oral human dose of 40 mg (based on a body surface area for a 60 kg person). Teratogenicity was not observed in animal reproduction studies with administration of oral esomeprazole (an enantiomer of omeprazole) magnesium in rats and rabbits during organogenesis with doses about 68 times and 42 times, respectively, an oral human dose of 40 mg esomeprazole or 40 mg omeprazole (based on body surface area for a 60 kg person). Changes in bone morphology were observed in offspring of rats dosed through most of pregnancy and lactation at doses equal to or greater than approximately 34 times an oral human dose of 40 mg esomeprazole or 40 mg omeprazole. When maternal administration was confined to gestation only, there were no effects on bone physeal morphology in the offspring at any age.

Interactions

Increased risk of hypomagnesaemia w/ diuretics. May increase INR and prothrombin time w/ warfarin. Increased risk of digoxin-induced cardiotoxic effects. May increase plasma concentration benzodiazepines (e.g. diazepam), clarithromycin and methotrexate. Decreased absorption of itraconazole, ketoconazole, posaconazole, dasatinib, iron salts. May prolong elimination of diazepam, cilostazol, phenytoin and ciclosporin. May reduce the antiplatelet effect of clopidogrel. Potentially Fatal: May decrease plasma concentrations and pharmacological effects of rilpivirine, nelfinavir and atazanavir.

Side Effects

Side effects of Omeprazole : 1-10% Headache (7%), Abdominal pain (5%), Diarrhea (4%), Nausea (4%), Vomiting (3%), Flatulence (3%), Dizziness (2%), Upper respiratory infection (2%), Acid regurgitation (2%), Constipation (2%), Rash (2%), Cough (1%) Frequency Not Defined Fracture of bone, osteoporosis-related, Hepatotoxicity (rare), Agranulocytosis, Anorexia, Gastric polyps, Hip fracture, Alopecia, Atrophic gastritis, Interstitial nephritis (rare), Pancreatitis (rare), Rhabdomyolysis, Taste perversion, Abnormal dreams, Toxic epidermal necrolysis (rare) Potentially Fatal: Anaphylaxis.

Mode of Action

Omeprazole is a substituted benzimidazole gastric antisecretory agent and is also known as PPI. It blocks the final step in gastric acid secretion by specific inhibition of H+/K+ ATPase enzyme system present on the secretory surface of the gastric parietal cell. Both basal and stimulated acid are inhibited.