Merck girds to battle Teva's generic Singulair

NEW YORK Feb 22 (Reuters) - Merck & Co (MRK.N) on Monday is expected to fight efforts by generic drugmaker Teva Pharmaceutical Industries (TEVA.TA) to introduce a copycat version of its biggest product, $4 billion-a-year asthma drug Singulair.

Although many analysts expect the larger Merck to prevail in the trial at federal court in Trenton, New Jersey, a victory by Teva could allow the Israeli company to launch its generic well before Singulair's U.S. patent lapses in August 2012.

"We expect the shares to be sensitive to any Singulair-related newsflow" from the trial, JP Morgan analyst Chris Schott said in a research note, referring to stocks of both drugmakers.

Teva in February 2007 informed Merck it had asked the U.S. Food and Drug Administration for permission to sell its generic.

Merck two months later sued Teva for patent infringement, thereby automatically barring the FDA from approving a generic for 30 months, or until a court decision against Merck.

"We believe the patent for Singulair in the U.S. is valid and has been infringed, and we will vigorously defend it against Teva," said Merck spokesman Ron Rogers.

Rogers said the trial could be wrapped up within a week, but declined to predict when Judge Garrett Brown would render a decision.

Teva officials could not be reached for comment.

Singulair has annual U.S. sales of about $3 billion, much of which would vanish once a cheaper generic appears. It is one of the world's best-selling medicines, although sales have slipped in the past year due to concerns the pill may increase the risk of suicide.

Merck is heavily dependent on revenue from Singulair, especially given a number of recent setbacks and disappointments that led to a slight decline in the drugmaker's fourth-quarter sales.

Sales of company cholesterol fighters Vytorin and Zetia have been badly hurt over the past year due to data from a pair of clinical trials that questioned their effectiveness.

Meanwhile, revenue from Merck's Fosamax osteoporosis drug have plunged due to recent launches of cheaper generics and the company has sharply cut revenue forecasts for its Gardasil vaccine against cervical cancer -- now facing competition from a vaccine sold by GlaxoSmithKline (GSK.L). (Editing by Maureen Bavdek)