FDA: ARYxs anticoagulant agent on track for approval

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The FDA has deemed it suitable for ARYx Therapeutics to continue its research surrounding its anticoagulant agent, tecarfarin (ATI-5923) to gain regulatory approval for the drug.

Tecarfarin, an oral anticoagulation therapy modeled after warfarin (Coumadin, Bristol-Myers Squibb), is utilized for the prevention of blood clots for a variety of indications including atrial fibrillation, prosthetic heart valve replacement or venous thromboembolism.

In its response, the FDA confirmed that the current pathway to seek approval for the drug remains on course after a Phase 2 and 3 EmbraceAC clinical trial showed that tecarfarin replicated its two previous Phase 2 clinical trials.

The drug, a selective inhibitor of vitamin K epoxide reductase (VKOR) enzyme, produces the same anticoagulation action as warfarin. In addition, tecarfarin was designed to avoid drug to drug interactions by avoiding the use of cytochrome P450 enzymes. This, the company said will cause tecarfarin to be more predictable than warfarin in avoiding the dangers associated with over-or-under therapeutic anticoagulation.

According to Fremont, Calif.-based ARYx, it sought guidance from the FDA on several issues during the development of the drug including: whether the maintenance of a patient's therapeutic level of anticoagulation, as measured by the International Normalized Ratio (INR), could continue to serve as a surrogate measure of outcome, and whether one additional clinical trial that compared the safety of tecarfarin to warfarin would establish tecarfarin’s superiority in the drug market and be sufficient for approval.

The agency said that INR measurements could be used as a surrogate endpoint and that an additional clinical trial comparing warfarin and tecarfarin to seek regulatory approval would be acceptable. The FDA recognized that endpoints of the trial should allow for a smaller clinical trial, of a shorter duration.