These days the U.S. Food and Drug Administration (FDA) is taking no chances when it comes to the safety of new drugs.
The increased scrutiny required before new drugs are approved is the result of a series of safety scares over the last decade, in particular the recent one over the diabetes drug Avandia produced by Wyeth and Merck's painkiller Vioxx in 2004.
The FDA's tough stance has seen four out of five attempts by drug company Wyeth, to launch new medicines on the U.S. market to be delayed.
The latest blow from the FDA comes as the agency now says it is reviewing the safety of its biggest seller, Nexium, and Prilosec.
The FDA is more likely nowadays to issue companies with "approvable" letters, which set conditions rather than granting final approvals.
This delays the launch of a new drug, which has financial implications for a company.
The FDA says a preliminary review of new data on the safety of two stomach drugs Prilosec and Nexium suggests that long term use of these medications does not lead to heart attacks and other heart related events.
In two studies involving patients with severe GERD who were randomly assigned to receive surgery or drug treatment (Prilosec), there were apparently more heart attacks, heart failure and heart related sudden deaths among the drug patients compared with the surgery patients.
The other study on Nexium (esomeprazole), has now gathered 5 years of follow up on patients but is not yet completed.
The initial results also showed a difference between the drug treatment and the surgery group, similar to the Prilosec study, but a more recent update has since shown that the incidence of cardiovascular events is largely similar between the two groups.
However the agency says a final decision and recommendation will not be made for three months's time.
At this point the FDA advises doctors and patients not to change their current practice with regard to their use of these drugs.