omeprazole magnesium

Action

Reduces gastric acid secretion and increases gastric mucus and bicarbonate production, creating protective coating on gastric mucosa and easing discomfort from excess gastric acid

Availability

Capsules (delayed-release): 10 mg, 20 mg, 40 mg

Powder for oral suspension (delayed-release): 2.5 mg, 10 mg in packets

Tablets (delayed-release): 20 mg

Indications and dosages

➣ Gastroesophageal reflux disease

Adults: 20 mg P.O. (capsules, powder) daily for 4 weeks

➣ Erosive esophagitis

Adults: 20 mg P.O. (capsules, powder) daily for 4 to 8 weeks

➣ Short-term treatment of active duodenal ulcer

Adults: 20 mg P.O. (capsules, powder) daily for 4 weeks. Some patients may need 4 additional weeks of therapy.

➣ To reduce risk of duodenal ulcers caused by Helicobacter pylori

Adults: 40 mg P.O. (capsules) daily in morning, given with clarithromycin t.i.d. for 2 weeks; then 20 mg daily for 2 weeks

➣ Gastric ulcers

Adults: 40 mg P.O. (capsules) daily for 4 to 8 weeks

➣ Pathologic hypersecretory conditions, including Zollinger-Ellison syndrome

Adults: Initially, 60 mg P.O. (capsules) daily; may increase up to 120 mg t.i.d. Divide daily dosages above 80 mg.

➣ Frequent heartburn (two or more episodes a week)

Adults ages 18 and older: 20 mg P.O. (OTC tablets, capsules, or powder) daily for 14 days

Off-label uses

• Posterior laryngitis

• To enhance pancreatin efficacy in treating steatorrhea in cystic fibrosis patients

Contraindications

• Hypersensitivity to drug or its components

Precautions

Use cautiously in:

• hepatic disease

• hypomagnesemia

• concurrent use of clopidogrel (avoid use)

• pregnant or breastfeeding patients

• children (safety not established).

Administration

• Give 30 to 60 minutes before a meal, preferably in morning.

• If desired, give concurrently with antacids.

• Know that if patient has ulcer at start of therapy, treatment may be extended.

• When giving through nasogastric tube, use powder for oral suspension, or separate capsule and mix pellets with water. Agitate syringe while injecting. After administration, flush with 30 to 60 ml of water.

• Don't crush capsules.

• Be aware that symptomatic response doesn't rule out gastric cancer.

Adverse reactions

CNS: dizziness, headache, asthenia

GI: nausea, vomiting, diarrhea, constipation, abdominal pain

Metabolic: hypomagnesemia

Musculoskeletal: back pain; fractures of hip, wrist, spine (with long-term daily use)

Respiratory: cough, upper respiratory tract infection

Skin: rash

Interactions

Drug-drug. Ampicillin, cyanocobalamin, iron salts, ketoconazole: reduced absorption of these drugs

Clarithromycin: increased omeprazole blood level

Clopidogrel: diminished antiplatelet activity

Diazepam, phenytoin, warfarin: prolonged elimination and increased effects of these drugs

Digoxin: increased digoxin absorption and blood level, possible digoxin toxicity

Drugs metabolized by CYP450 system: competitive metabolism

Methotrexate: increased methotrexate serum level

Penicillins: serious and occasionally fatal hypersensitivity reactions including anaphylaxis

Rifampin: substantially decreased omeprazole concentrations

Drug-diagnostic tests. Alanine phosphatase, alkaline aminotransferase, aspartate aminotransferase, bilirubin: increased levels

Gastrin: increased level during first 1 to 2 weeks of therapy

Serum chromogranin A: increased level may cause false-positive results in diagnostic investigations for neuroendocrine tumors

Serum magnesium: decreased level

Drug-herbs. St John's wort: substantially decreased omeprazole concentration

Patient monitoring

• Assess vital signs.

• Check for abdominal pain, emesis, diarrhea, or constipation.

• Evaluate fluid intake and output.

• Watch for elevated liver function test results (rare).

• Monitor magnesium level before starting drug and periodically thereafter in patients expected to be on long-term treatment or who take proton pump inhibitors with other drugs such as digoxin or drugs that may cause hypomagnesemia.

Patient teaching

• Tell patient to take 30 to 60 minutes before a meal, preferably in morning.

• Instruct patient to swallow capsules or tablets whole and not to chew or crush them. If he can't swallow capsule, tell him he may open it, carefully sprinkle and mix entire contents into 1 tbsp of cool applesauce, and swallow immediately with glass of water.

• Instruct patient on how to use delayed-release oral suspension: Empty contents of a 2.5-mg packet of powder into a container with 5 ml of water or 10-mg packet of powder into a container with 15 ml of water; don't use other liquids or foods. Stir and allow drug to thicken for 2 to 3 minutes. Stir well and drink within 30 minutes. If any drug remains after drinking, add more water to container, stir, and drink immediately.

• Inform patient taking OTC delayedrelease tablets for heartburn that full effect may take 1 to 4 days. Advise him not to take tablets for more than 14 days without consulting health care professional.

• Advise patient to avoid St John's wort while taking this drug.

• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.

• As appropriate, review all other significant adverse reactions and interactions, especially those related to the drugs and tests mentioned above.