Bayer’s woes with Trasylol, used to prevent or reduce blood loss during surgery, look set to continue after US health officials said they have approved a new label which highlights the possible risk of kidney damage associated with taking the drug.

The Food and Drug Administration said that Trasylol (aprotinin), the only drug approved by the agency to reduce blood loss during coronary artery bypass surgery, needs a new label which states that it should only be used on patients who are at an increased risk for blood loss and blood transfusion during the surgical procedure.

The agency also said the drug will come with a stronger warning about possibly anaphylactoid reactions, and added that patients should not receive Trasylol if they have already been given the drug within the past year. It also said that additional warnings may need to be added in the future.

FDA began reassessing the safety of the drug earlier this year, when two separate studies suggested links to heart attack, stroke and kidney problems. In September, Bayer submitted new data to the FDA about risks of Trasylol but crucially this came days after advisory panel meeting was held to review the drug's labelling and found it to be safe and effective when used to prevent blood loss in patients undergoing coronary artery bypass grafting.

Bayer admitted that it should have disclosed the results earlier and suspended two senior staff members as a result of the incident. A US lawyer has been called in to examine the case.

The drug is a big earner for Bayer but the effect of all the recent controversy on third-quarter sales of Trasylol was considerable, as they fell some 40% on the like, year-earlier period to 38 million euros.