On May 31, 2007, Pfizer won in a significant Patented Medicines (Notice of Compliance) Regulations appeal proceeding against Apotex. The litigation centred around two patents for quinapril, the active ingredient in Pfizer's ACE-inhibiting, hypertension drug Accupril: the 615, which Apotex claimed it was not infringing, and the 330, which Apotex argued was invalid. Apotex prevailed in the Federal Court on both patents, and would have gained market entry had the Court of Appeal not unanimously reversed on both patents, finding that Apotex was infringing the 615 and that the 330 was valid. Pfizer's market position on Accupril will be protected until 2019, when the 330 patent expires.