The Medicines Company said on a press release on Wednesday that it received a not approvable letter from U.S. regulators on a supplemental New Drug Application for an additional dosing regimen for Angiomax in the treatment of acute coronary syndromes.

Shares of Medicines Company closed 7.37 percent down to $18.47 in Nasdaq today. The company said the letter sent by the Food and Drug Administration indicated that the basis of its decision involved the appropriate use and interpretation of non-inferiority trials including ACUITY.

The Company disagrees with the Agency on these issues and has initiated discussions to address them Medicines Co.said in a statement.

The medical group believes that the ACUITY results are consistent with those demonstrated in clinical trials of over 47,000 patients with cardiovascular risk, which demonstrate that utilizing Angiomax (known generically as bivalirudin) instead of heparins reduces bleeding and costs in addition to protection against ischemic events.

The Medicines Company reaffirmed its 2008 Angiomax U.S. sales outlook of $310 to $320 million. As of March 2008, more than 44 percent of patients undergoing percutaneous coronary intervention receive Angiomax as their baseline anti-coagulant, the company said.