Table 1. Frequencies of adverse events resulting from indication of omeprazole that were reported in studies published up to 2016.
| Assessment | Type of ADE | Frequency | Description |
|---|---|---|---|
| Safety | ADR (n = 47) | Common reaction (≥ 1% and < 10%) | Headache, constipation, diarrhea, abdominal pain, back pain, flatulence, respiratory tract infection and maculopapular rash.32,33,34,35,36,37 |
| Uncommon reaction (≥ 0.1% and < 1%) | Eczematous eruption, insomnia, somnolence, urticaria, urticaria vasculitis and vertigo.38 | ||
| Rare reaction (≥ 0.01% and < 0.1%) | Angioedema, arthralgia, muscle pain, erythema multiforme, weakness, metallic taste in the mouth, allergic reaction, Steven-Johnson’s syndrome and thirst.38 | ||
| Post-marketing experience | Unstable angina, increased risk of fractures, cancer, cystitis, ulcerative colitis, stomatitis, abnormal renal function, hypergastrinemia, decreased levels of vitamin B12, increased creatinine levels, hypomagnesemia.14,39,40,41,42,43 | ||
| Potential events not described in omeprazole monograph (n = 28) | Miscarriage, proliferative changes, increased levels of chromogranin A, increased levels of fibroblast growth factor 2, chills, cardiovascular events (myocardial infarction, heart failure, stroke, ischemic stroke, pulmonary embolism and thrombosis), scarlet fever, hyperglycemia, mononucleosis infection, gastrointestinal bleeding, nasopharyngitis, otitis media, loss of libido, rhinitis, dementia, metabolic syndrome and hepatic steatosis, low sperm motility, increased risk of fibrosis progression, cirrhosis, hepatic decompensation and development of hepatocellular carcinoma.44,45,46,47,48,60,65,66,67 | ||
| DI (n = 6) | Omeprazole and clopidogrel: cardiovascular death, myocardial infarction, inhibition of the effect of clopidogrel, increased leukocyte and platelet levels and increased brain adverse events.75,76 | ||
| Omeprazole and acenocoumarol: increased anticoagulant effect of acenocoumarol.77 | |||
| Omeprazole and mycophenolate mofetil: reduced absorption of mycophenolic acid.49 | |||
| Efficacy | TI (n = 5) | Some patients did not respond to omeprazole therapy and continued with colitis symptoms and gastrointestinal discomforts. Omeprazole failed to control the gastric acidity of some patients.13 | |
ADE = adverse drug event; ADR = adverse drug reaction; DI = drug interaction; TI = therapeutic ineffectiveness. The frequency of adverse reactions was classified according to the leaflet of the reference drug product, except for the 28 studies for which there was no information on the leaflet.