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U.S. Department of Health and Human Services


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Early Communication About an Ongoing Safety Review of Omeprazole (Prilosec) and Esomeprazole (Nexium)


This information reflects FDA’s current analysis of available data concerning these drugs. Posting this information does not mean that FDA has concluded there is a causal relationship between the drug products and the emerging safety issue.  Nor does it mean that FDA is advising health care professionals to discontinue prescribing these products. FDA is considering, but has not reached a conclusion about whether this information warrants any regulatory action. FDA intends to update this document when additional information or analyses become available.

FDA has received and is reviewing new safety data about Prilosec (omeprazole) and Nexium (esomeprazole).  On May 29, 2007, AstraZeneca, the manufacturer of Prilosec (omeprazole) and Nexium (esomeprazole), sent FDA and other regulatory authorities world-wide their preliminary review of new data from two small long-term clinical studies in patients with severe gastroesophageal reflux disease (GERD).  In both studies, patients were to be randomly assigned to receive treatment with a drug (either omeprazole or esomeprazole) or to have surgery to control their GERD.  The results from the study of Prilosec and analyses from an ongoing study of Nexium raised concerns that long-term use of Prilosec or Nexium may have increased the risk of heart attacks, heart failure, and heart-related sudden death in those patients taking either one of the drugs compared to patients who received surgery. 

Since May 29, the company has provided FDA with a large amount of additional data, including more information on patient follow-up from the two long-term studies mentioned above, and pooled analyses of other controlled clinical studies, including placebo-controlled trials of up to two-year’s duration. At this time, FDA’s preliminary conclusion is that collectively, these data do not suggest an increased risk of heart problems for patients treated with omeprazole or esomeprazole.  Therefore, FDA does not believe that healthcare providers or patients should change either their prescribing practices or their use of these products at this time.

This early communication is in keeping with FDA’s commitment to inform the public about its ongoing safety reviews of drugs.  FDA plans to complete its review within three months, and will communicate its conclusions and any resulting recommendations to the public at that time. 

What does FDA know now about these data? 

A 14-year study comparing treatment with the drug omeprazole to surgery in patients with severe GERD found that more patients treated with omeprazole had heart attacks, heart failure, and heart-related sudden death than did the patients who had surgery.  The difference between the two groups of patients was seen within the first year of the study, and continued over time.  A second, still ongoing, study comparing esomeprazole to surgery had five year follow-up information on patients.  While the initial data from this study suggested a difference between treatments in the rate of cardiovascular events, an updated report submitted by AstraZeneca found that the number of patients who experienced heart problems was similar in both treatment groups. 

While both of these studies collected safety data, the study protocols did not specify how heart problems, such as heart attacks, were to be defined or documented.  As a result, evaluating the information that has been gathered about the safety of either drug in these studies is difficult.

Also, many of the patients who were randomized to the group that was to have surgery withdrew from the study without ever undergoing the surgical procedure.  The patients who did undergo surgery tended to be younger, and less likely to have a past history of heart problems or risk factors for heart problems, than those who were treated with one of the drugs.  These differences between the two groups of patients could have biased and significantly influenced the safety data from these studies. 

Finally, FDA’s preliminary conclusion about the information from these two studies is further supported by an additional analysis of 14 comparative studies of omeprazole, of which four were placebo-controlled.  Patients in these studies were treated for up to two years.  In these studies, there were fewer heart attacks or other heart problems reported in the patients treated with omeprazole compared to patients that were given a placebo. Although these studies were not specifically conducted to assess the risk of heart problems, and patient follow-up is incomplete, they do not suggest an increased risk of heart problems with the use of omeprazole. FDA will continue its review of all available data.

Based on everything we know now, FDA’s preliminary conclusion is that the observed difference in risk of heart attacks and other heart related problems seen in early analyses of the two small long-term studies is not a true effect. 

Prilosec and Nexium are members of a class of drugs called proton pump inhibitors (PPIs) and work by reducing the amount of acid produced by the stomach. Both drugs are used for the treatment of gastroesophageal reflux disease (GERD) including a condition where the lining of the esophagus wears away (erosions), and for maintenance of healing erosions of the esophagus. They are also used for the treatment of ulcers. Prilosec (omeprazole) and Nexium (esomeprazole) are available by prescription. Prilosec is also sold over-the-counter for frequent heartburn. 


Date created: August 9, 2007, updated December 10, 2007