US company Northfield Laboratories came under fire yesterday after an open letter by three medical researchers claimed a trial of its blood substitute product PolyHeme could put patients at risk.

The Phase III trial’s protocol randomises trauma patients to either PolyHeme or regular blood transfusions once they arrive in hospital. But because donated blood is of proven benefit - and the patients often cannot give informed consent to receive an alternative - the trial is ethically compromised, according to the authors, who have published their letter on the website of the American Journal of Bioethics.

Northfield has been under pressure over PolyHeme’s development for some time. The Wall Street Journal published an article last month alleging that the company tried to hide crucial details about a trial of PolyHeme reported in 2000. 10 patients treated with PolyHeme in the study suffered heart attacks, with none observed in the control group. Two of them died.

“We have made no effort to discourage the publication of the … data and, in fact three publications have resulted from the study with the fourth expected soon,” said Northfield chief executive Steven Gould. He also said the analysis suggests the cardiovascular events “were not due to a direct pharmacologic effect of PolyHeme, but to complex fluid management issues in these patients.”

Meanwhile, Senate Finance Committee chairman Charles Grassley has asked the US Food and Drug Administration (FDA) to publicly address the ethics of the study.

If approved, PolyHeme could revolutionise the care of trauma patients because, unlike blood, it could be given in the ambulance on the way to hospital to patients of any blood type.