Eli Lilly and partner Daiichi Sankyo have been forced to release a statement reassuring investors their blood-thinner prasugrel will continue to move through the approval process amid media speculation US regulators are again delaying a decision.

Touted as a potential blockbuster, prasugrel, a treatment for acute coronary syndromes, has been delayed twice in the US Food and Drug Administration approval process.

Reports out on Friday suggested a decision on the drug, which would be marketed under the name Effient, could be put off until after March next year based on FDA meetings.

Lilly and Daiichi Sankyo “reiterated” that the companies were continuing to discuss the review of the New Drug application with the FDA.

“Daiichi Sankyo and Lilly are engaged in an ongoing dialogue with the FDA. We remain confident in the overall benefit-risk profile of prasugrel, and we believe this drug should be approved so that we can bring this valuable treatment option to ACS patients,” said Jennifer Stotka, Vice President of Global regulatory Affairs at Lilly.

A New drug Application was submitted to the FDA in December 2007, and in February the agency announced a six-month priority review for the application.

However, in June, the FDA announced it was delaying the application, saying that the weight of supplemental information filed on the drug meant it had to put back its action date by three months to September 26. The second deadline was also missed.

While the submission is both large and complex, reports suggest there is disagreement within the FDA over the approval.

Critics of the delay have accused the FDA for being over cautious but a large part of the approval will be based on the TRITON trial, which had mixed results.

According to the study, prasugrel produced a 19% reduction in relative risk for the endpoint of cardiovascular death, non-fatal heart attack or non-fatal stroke when compared with Sanofi-Aventis/Bristol-Myers Squibb’s Plavix (clopidogrel). However, the data also revealed that prasugrel-treated patients also experienced a statistically significant 32% increase in minor and major bleeding.

Lilly and Daiichi Sankyo said in the statement they had not been notified of any regulatory action for the NDA or of any decision to have an advisory committee review the drug.