Pozen (Nasdaq: POZN) has sold the U.S. royalty rights for migraine drug Treximet to Canada's national pension fund, CPPIB Credit Investments, in a $75 million deal.

The terms of the deal give the Chapel Hill, N.C., pharmaceutical company a 20% interest in any royalties received by the pension fund starting April 1, 2018, according to a filing with the Securities and Exchange Commission.

Treximet is marketed in the United States by Pozen drug partner GlaxoSmithKline (NYSE: GSK). Pozen has the right to develop and market a lower dose of the drug outside the country, while Glaxo holds the license to develop and market Trexmet in the United States, according to Reuters.

For the first nine months of 2011, revenues from royalties on Treximet were $12.2 million, according to the company's third-quarter earnings report, making it the best money earner in its drug arsenal.

Despite the end of regulatory exclusivity for the drug in April, Pozen has successfully fought numerous companies developing generic versions of Treximet in a court case against Par Pharmaceutical (NYSE: PRX), Alphapharm, and Dr. Reddy's Laboratories (NYSE: RDY), allowing Treximet to continue without generic competition until its patents expire; two expire in 2017 and one expires in 2025.

Pozen could not be reached for comment.

A spokeswoman for the pension fund said: "CPPIB's acquisition of the royalty interest in Pozen's prescription drug Treximet is part of an Intellectual Property strategy that the organization launched in 2010. Royalty investing can provide attractive risk-adjusted returns for our fund. To date, we have completed intellectual property transactions totaling approximately US$350 million. We will continue to look for investment opportunities in this area."