AstraZeneca has been boosted by a safety review carried out by US regulators which shows that the blockbuster antiulcerant Nexium and its predecessor Prilosec do not increase the risk of heart attacks.

The US Food and Drug Administration has completed a six-month review which began when AstraZeneca sent the agency, and other regulatory authorities worldwide, a preliminary review of new data from two small long-term clinical studies of Nexium (esomeprazole) and Prilosec (omeprazole) in patients with severe gastroesophageal reflux disease.

The FDA said in August that the two studies showed no increased risk of heart problems associated with long-term use of the drugs. It has since reviewed 14 comparative studies of Prilosec, four of which were placebo-controlled and although they were not specifically conducted to assess the risk of heart problems, and patient follow-up was incomplete, the agency has come to the same conclusion.

The FDA noted that “based on everything now known at the agency, the reported difference in the frequency of heart attacks and other heart-related problems seen in the earlier analyses of the two small long-term studies does not indicate the presence of a true effect”. It added that healthcare providers should “continue to prescribe, and patients continue to use, these products as described in the labelling”.

The news comes as a relief to AstraZeneca although it always expressed confidence in the safety profiles of the drugs. Nevertheless, any label change could have damaged sales, particularly those of Nexium which brought in $1.29 billion in the third quarter.

However this does not mean the end of the FDA’s interest in Nexium and Prilosec. Following on from a study in the Journal of the American Medical Association last December, the agency is now looking at whether proton pump inhibitors, such as the two AstraZeneca drugs, increase the risk of hip fractures.

The JAMA article was based on a study which suggested that long-term use of PPIs could lead to an increase in the risk hip fractures in adults over 50. AstraZeneca is co-operating with the agency and does not believe there is any link between Nexium or Prilosec and hip fractures.