U.S. regulators have accepted an experimental fish oil-based heart drug from AstraZeneca for review and will make a decision on whether to approve it by next May.

Epanova, for treating people with very high levels of fatty triglycerides in their blood, was developed by Omthera Pharmaceuticals, which AstraZeneca acquired earlier this year.

AstraZeneca said that the U.S. Food and Drug Administration had set a date of May 5, 2014 to act on the Epanova submission.

Buying Omthera forms part of a drive by Chief Executive Pascal Soriot to revive AstraZeneca's fortunes through a series of bolt-on deals in core areas, including cardiovascular medicine.

The acquisition pitches AstraZeneca into competition with rivals including GlaxoSmithKline and Amarin that already have similar heart-friendly fish oil drugs approved.

AstraZeneca's sales and profits are falling as older medicines lose patent protection and the company badly needs new products to replace former big sellers like the antipsychotic Seroquel, which lost exclusivity last year.

Cardiovascular medicine is a key area for AstraZeneca, whose top-selling drug is the cholesterol fighter Crestor. The British-based group is working on a fixed-dose combination of Crestor and Epanova that, if successful, would extend the Crestor franchise beyond 2016, when the drug's U.S. patent ends.

AstraZeneca is also banking on another heart drug, Brilinta, to drive sales, although this product has so far been slow to take off.