US regulators have issued an alert to patients and health care professionals over Abbott Laboratories’ antibiotic Biaxin (clarithromycin), after the drug was linked to a higher chance of death from heart problems in patients given the drug during a study carried out in Denmark.

But the Food and Drug Administration (FDA) says it is not, at present, recommending any label changes for Biaxin, which is most commonly prescribed for treating bacterial respiratory infections, as previous trials have suggested a higher risk of death from use of the drug.

According to the agency, the Danish study is the first time that an increase in deaths patients with heart disease was recorded after use of the drug, and Abbott said it considers the findings completely random, noting that they go against numerous other studies involving Biaxin and other medicines in its class.

This unexpected trend emerged only one year (or longer) after Biaxin was given to patients in the study, the FDA noted in its alert, adding that the mechanism by which two weeks of taking the medicine could increase mortality after one year is still unclear.

But as the agency, which has faced mounting criticism of late over the way it deals with drug safety issues, has not yet had access to data from the study, says the alert is just a preliminary analysis, with further action to be decided only once it has evaluated the results.