An unfavorable Vascepa patent ruling from the Court of Appeals Federal Circuit can place the shares of Amarin (AMRN) in the $3 range, Northland analyst Carl Byrnes tells investors in a research note.

However, a favorable ruling can take the shares above $25, adds the analyst. Amarin closed yesterday down 31% to $5.04 after oral arguments were heard in the patent appeal case. Prospects of a reversal for Amarin on appeal dampened yesterday to around 25%, Byrnes contends. Hikma provided "clear and convincing" evidence to support invalidating the six Amarin patents on the basis of obviousness, says the analyst. Nonethless, Byrnes still believes potential generic entrants would encounter problems in obtaining commercial quantities of FDA-grade icosapent ethyl. As such, even with potential generic competition, Vascepa can retain the "lion's share of the market," according to the analyst.

Byrnes keeps an Outperform rating on Amarin with a $15 price target.