Merck suffered another huge blow after a federal appeals court judge invalidated its patent for Fosamax, the company's second best-selling product. Last week's court decision opens the drug to generic competition in 2008, 10 years earlier than Merck had expected. The court vacated a lower court decision against generic drug maker Teva Pharmaceuticals that found the Merck patent on Fosamax was valid. The patent was due to expire in July 2018. Fosamax had worldwide sales of $3.2 billion for 2004. That number is second only to its top-selling Zocor, which reached sales of $5.2 billion. Zocor's patent protection expires next year. Merck said in a statement after the verdict that it disagreed with the ruling "and is considering its options, including a request for reconsideration by the court of appeals." The ruling came on the same day as the Securities and Exchange Commission opened an investigation into Merck's handling of its recall of Vioxx last year. The SEC is expected to question what Merck chief executive Raymond Gilmartin told investors about the drug prior to the recall.