fizer’s Viagra (sildenafil) will be protected from generic competition in Canada until its patent expires in 2014, the country’s Federal Court ruled yesterday.

Generic drugmakers, including Teva’s unit Novopharm, had alleged the patent covering the blockbuster erectile dysfunction drug was invalid because of “obviousness” and “lack of utility” – an allegation rejected by the Court.

Novopharm is now prohibited from introducing a generic version until 2014.

Meanwhile, Pfizer says it has made the next move in its planned acquisition of Wyeth, after the US Securities and Exchange Commission declared its registration statement "effective". Wyeth's annual meeting of stockholders will take place on July 20 at which voting on the merger agreement will take place.