Inspire Pharmaceuticals of the USA has stopped a Phase II trial of its antiplatelet drug for patients undergoing coronary artery bypass graft surgery after patients in the study experienced ‘a range of bleeding complications’.

INS50589, which works by inhibiting the platelet P2Y12 adenosine diphosphate receptor, had been given to 27 out of a target of 160 patients in the study before an interim analysis uncovered the unacceptably high rate of bleeds with the drug. There were no deaths reported in the study.

Inspire senior vice president of development, Donald Kellerman, said that the company would conduct a thorough analysis of the study but that it is likely that the company will not invest further in the project.

News of the disappointment came too late in the day yesterday to affect Inspire’s share price, which closed unchanged at $4.82.

INS50589 had been something of a speculative venture for Inspire, which focuses primarily on ophthalmic and respiratory medicines. Its pipeline includes Prolacria (diquafasol tetrasodium) for dry eye, still languishing in a US Food and Drug Administration (FDA) review despite being filed in 2003, and INS37217 (denufosol tetrasodium) for cystic fibrosis in Phase III testing.