AstraZeneca buys heart firm Omthera for up to $443 million LONDON (Reuters) - AstraZeneca is to buy Omthera Pharmaceuticals for as much as $443 million to build up its cardiovascular drug business, a priority area for Britain's second-biggest drugmaker. The acquisition of the U.S.-based specialist in fish oil-derived medicine underscores a drive by new Chief Executive Pascal Soriot to revive AstraZeneca's fortunes through a series of bolt-on deals. It is his second purchase in the cardiovascular field, following the acquisition last month of AlphaCore Pharma, a small early-stage U.S. biotechnology company. The latest transaction pitches AstraZeneca into competition with rivals including GlaxoSmithKline that already sell heart-friendly fish oil drugs. Omthera's leading drug has already completed final-stage clinical tests and has the potential to be combined with AstraZeneca's blockbuster cholesterol fighter Crestor. Helvea analyst Odile Rundquist said the deal was "a good move as it perfectly complements AstraZeneca's cardiovascular portfolio." 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. AstraZeneca said on Tuesday it had entered into a definitive agreement to buy Omthera for $12.70 per share, or approximately $323 million, a premium of 88 percent to Omthera's closing price on Friday. In addition, Omthera shareholders will get "contingent value rights" (CVRs) of up to approximately $4.70 per share, or $120 million in total, depending on the success of Omthera's experimental drug Epanova, for treating patients with very high triglycerides, a type of blood fat that is bad for the heart. CVRs are being used increasingly in deals in the pharmaceutical and biotechnology market to bridge differing expectations surrounding new drugs whose final sales are uncertain. Shares in Omthera leapt 90 percent to $12.80 in premarket dealings on Nasdaq. Epanova is an ultra-pure mixture of the free fatty acid forms of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), derived from fish oil. It has already completed final-stage Phase III clinical trials and is set to be submitted for U.S. regulatory approval around the middle of this year. The new drug will compete with other fish oil-based medicines such as GlaxoSmithKline's Lovaza and Amarin's recently approved Vascepa. AstraZeneca had, at one stage, been tipped as a possible buyer of Amarin. Lovaza last year generated sales of 607 million pounds ($917 million) for GSK in the United States and Puerto Rico, where the company has marketing rights to the product. Cardiovascular medicine is a key area for AstraZeneca, whose top-selling drug is Crestor. The British-based group said it intended to conduct a series of clinical studies testing a fixed-dose combination of Crestor and Epanova. The new combination, 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 as older products go off patent. Shares in AstraZeneca were up 3.2 percent at 3536.5 pence in a strong London stock market by 1054 GMT. In addition to news of the Omthera deal the stock was buoyed by news of a temporary blockage on U.S. sales of rival generic versions of its asthma drug Pulmicort Repsules, which was announced late on Friday. The deal to buy Omthera has the backing of investors representing 60 percent of the Princeton, New Jersey-based company's shares. It is expected to close in the third quarter of 2013. Editing by David Holmes and Greg Mahlich