warnings and cautions
5 WARNINGS AND PRECAUTIONS Symptomatic response does not preclude the presence of gastric malignancy (5.1) Atrophic gastritis: has been noted with long-term therapy (5.2) Bone Fracture: Long-term and multiple daily dose PPI therapy may be associated with an increased risk for osteoporosis-related fractures of the hip, wrist or spine. (5.3) Diminished anti-platelet activity of clopidogrel due to impaired CYP2C19 function by 80 mg omeprazole (5.4) Triple therapy for H. pylori – there are risks due to antibiotics; see separate prescribing information for individual antibiotics (5.5, 5.6) Hypomagnesemia has been reported rarely with prolonged treatment with PPIs (5.7) Avoid concomitant use of PRILOSEC with St John’s Wort or rifampin due to the potential reduction in omeprazole concentrations (5.8, 7.3) Interactions with diagnostic investigations for Neuroendocrine Tumors: Increases in intragastric pH may result in hypergastrinemia and enterochromaffin-like cell hyperplasia and increased Choromogranin A levels which may interfere with diagnostic investigations for neuroendocrine tumors. (5.9, 12.2) 5.1 Concomitant Gastric Malignancy Symptomatic response to therapy with omeprazole does not preclude the presence of gastric malignancy. 5.2 Atrophic Gastritis Atrophic gastritis has been noted occasionally in gastric corpus biopsies from patients treated long-term with omeprazole. 5.3 Bone Fracture Several published observational studies suggest that proton pump inhibitor (PPI) therapy may be associated with an increased risk for osteoporosis-related fractures of the hip, wrist, or spine. The risk of fracture was increased in patients who received high-dose, defined as multiple daily doses, and long-term PPI therapy (a year or longer). Patients should use the lowest dose and shortest duration of PPI therapy appropriate to the condition being treated. Patients at risk for osteoporosis-related fractures should be managed according to established treatment guidelines. [ see Dosage and Administration (2) and Adverse Reactions (6.3) ] 5.4 Diminished Anti-platelet Activity of clopidogrel due to Impaired CYP2C19 Function by Omeprazole Clopidogrel is a prodrug. Inhibition of platelet aggregation by clopidogrel is entirely due to an active metabolite. The metabolism of clopidogrel to its active metabolite can be impaired by use with concomitant medications, such as omeprazole, that interfere with CYP2C19 activity. Avoid concomitant use of clopidogrel and omeprazole. Co-administration of clopidogrel with 80 mg omeprazole, a proton pump inhibitor that is an inhibitor of CYP2C19, reduces the pharmacological activity of clopidogrel if given concomitantly or if given 12 hours apart [ see Drug Interactions (7) ]. 5.5 Combination Use of PRILOSEC with Amoxicillin Serious and occasionally fatal hypersensitivity (anaphylactic) reactions have been reported in patients on penicillin therapy. These reactions are more likely to occur in individuals with a history of penicillin hypersensitivity and/or a history of sensitivity to multiple allergens. Before initiating therapy with amoxicillin, careful inquiry should be made concerning previous hypersensitivity reactions to penicillins, cephalosporins or other allergens. If an allergic reaction occurs, amoxicillin should be discontinued and appropriate therapy instituted. Serious anaphylactic reactions require immediate emergency treatment with epinephrine. Oxygen, intravenous steroids and airway management, including intubation, should also be administered as indicated. Pseudomembranous colitis has been reported with nearly all antibacterial agents and may range in severity from mild to life-threatening. Therefore, it is important to consider this diagnosis in patients who present with diarrhea subsequent to the administration of antibacterial agents. Treatment with antibacterial agents alters the normal flora of the colon and may permit overgrowth of clostridia. Studies indicate that a toxin produced by Clostridium difficile is a primary cause of “antibiotic-associated colitis.” After the diagnosis of pseudomembranous colitis has been established, therapeutic measures should be initiated. Mild cases of pseudomembranous colitis usually respond to discontinuation of the drug alone. In moderate to severe cases, consideration should be given to management with fluids and electrolytes, protein supplementation, and treatment with an antibacterial drug clinically effective against Clostridium difficile colitis. 5.6 Combination Use of PRILOSEC with Clarithromycin Clarithromycin should not be used in pregnant women except in clinical circumstances where no alternative therapy is appropriate. If pregnancy occurs while taking clarithromycin, the patient should be apprised of the potential hazard to the fetus. (See Warnings in prescribing information for clarithromycin.) Co-administration of omeprazole and clarithromycin has resulted in increases in plasma levels of omeprazole, clarithromycin, and 14-hydroxy-clarithromycin. [ See Clinical Pharmacology (12) ] Concomitant administration of clarithromycin with cisapride or pimozide, is contraindicated. 5.7 Hypomagnesemia Hypomagnesemia, symptomatic and asymptomatic, has been reported rarely in patients treated with PPIs for at least three months, in most cases after a year of therapy. Serious adverse events include tetany, arrhythmias, and seizures. In most patients, treatment of hypomagnesemia required magnesium replacement and discontinuation of the PPI. For patients expected to be on prolonged treatment or who take PPIs with medications such as digoxin or drugs that may cause hypomagnesemia (e.g., diuretics), health care professionals may consider monitoring magnesium levels prior to initiation of PPI treatment and periodically. [ See Adverse Reactions (6.3) ] 5.8 Concomitant use of PRILOSEC with St John’s Wort or rifampin Drugs which induce CYP2C19 or CYP3A4 (such as St John’s Wort or rifampin) can substantially decrease omeprazole concentrations. [ See Drug Interactions (7.3) ] Avoid concomitant use of PRILOSEC with St John’s Wort or rifampin. 5.9 Interactions with Investigations for Neuroendocrine Tumors Serum chromogranin A (CgA) levels increase secondary to drug-induced decreases in gastric acidity. The increased CgA level may cause false positive results in diagnostic investigations for neuroendocrine tumors. Providers should temporarily stop omeprazole treatment before assessing CgA levels and consider repeating the test if initial CgA levels are high. If serial tests are performed (e.g. for monitoring), the same commercial laboratory should be used for testing, as reference ranges between tests may vary.