AstraZeneca will pay a maximum of $443 million for lipid lowering specialist Omthera Pharma to gain access to its anti-triglyceride drug Epanova.

Under the terms of the agreement, AstraZeneca will acquire Omthera for $12.70 per share, or around $323 million.

But addition to the cash payment, each Omthera shareholder will receive contingent value rights of up to $4.70 per share – or around $120 million in total - if specified milestones related to investigational drug Epanova are achieved.

This will bring the total potential acquisition cost to around $443 million. Epanova is in late-stage clinical trials for the potential treatment of patients with very high triglycerides.

AstraZeneca will hope that the drug will help shore up and eventually help replace some of the sales of Crestor, its best-selling medicine with $6.3 billion in 2012 revenue.

But this treatment will face generic competition in the USA from 2016, and its sales are already sliding since generic forms of Pfizer’s Lipitor cholesterol drug became available in 2011.

Gerald Wisler, president and chief executive of Omthera, said: “We are delighted to be joining AstraZeneca, a leading pharmaceutical company with a proven track record in the development and commercialisation of global brands in the area of cardiovascular disease.

“We believe strongly that AstraZeneca can maximise the value of Epanova not only as a monotherapy treatment for dyslipidemia but also as a treatment for cardiovascular disease in combination with Crestor.”

AstraZeneca plans to seek approval to sell Omthera’s Epanova “as soon as possible” as a single therapy and in combination with Crestor.

Epanova is an omega-3 free fatty acid composition that has been shown to bolster levels of eicosapentaenoic acid and docosahexaenoic acid significantly in the blood.

The product would compete with GlaxoSmithKline Lovaza and Amarin’s Vascepa, which also are used in patients with high triglyceride levels.