Jan 21 (Reuters) - Amarin Corp Plc's shares fell more than 25 percent in premarket trading after U.S. health regulators rejected a preset testing process as the company seeks broader use of its blood fat-lowering drug.
The Irish drugmaker said it planned to appeal the decision, but that it does not expect a decision on the extended use of the drug while the appeal is pending.
The U.S. Food and Drug Administration had in October revoked a Special Protocol Assessment (SPA) agreement covering a large late-stage trial of the drug, Vascepa.
Such deals provide companies assurance that the design and analysis of a trial are adequate to support a marketing application submission with the U.S. health regulator.
Following an appeal from Amarin, the regulator said it would determine by Jan. 15 whether it would reconsider that decision.
The SPA was revoked after an advisory panel to the FDA had recommended against the drug's approval for use in a broader patient population until results from the larger trial had been analyzed.
The regulator had then said a substantial scientific issue essential to determining the effectiveness of Vascepa in the expanded population was identified only after the trial began.
Vascepa was approved in 2012 to reduce high levels of triglycerides - a type of blood fat that can increase the risk of heart disease - in patients not taking cholesterol-lowering statins such as Pfizer Inc's Lipitor.
In a bid to broaden the drug's market and improve sales, Amarin applied last February for approval to sell Vascepa to patients with blood fat abnormalities who are at high risk of coronary heart disease and are also taking statins.
(Reporting by Natalie Grover in Bangalore; Editing by Saumyadeb Chakrabarty)