Sun creates potential early challenge to Wyeth's Effexor

PHILADELPHIA Wyeth Pharmaceuticals is about to be hit by a generic launch, according to published reports. Wyeth’s antidepressant drug, Effexor, is on pace to have sales exceed $3.7 billion, but Sun Pharmaceuticals has discovered a way to challenge one of the patents to the multibillion-dollar drug and will be allowed to market a generic much sooner than Wyeth had expected competition.

Sun has applied to the Food and Drug Administration to sell a drug with the same active ingredient as Effexor XR, but the drug will be available in a tablet, rather than the capsule form of Wyeth’s version of the drug.

FDA approval of what is likely to be a lower-priced drug from Sun might come when patent protection for Effexor’s active ingredient, venlafaxine, runs out in June 2008. Patent protection for the capsule formulation expires later. Sun’s different formulation should allow it to sidestep Wyeth’s patent rights, and Wyeth already has told Sun it won’t sue for patent infringement.

Bank of America estimated the Sun version of Effexor XR could take 10 percent to 15 percent of the market share for the drug. That would represent more than $500 million in lost sales annually for Wyeth.

Wyeth has most likely played down the impact of the Sun version of Effexor XR because, for one, the Sun pills are unlikely to be certified by the FDA as the exact equivalent to Effexor XR—because of the different formulation. As a result, Sun’s product won’t benefit from state laws that require pharmacies to automatically substitute generics for branded drugs. The laws require generics to be exact copies, including the same formulation. For Sun to get its pills into patients’ hands, doctors would have to write new prescriptions specifically for the Sun product, not Effexor XR.

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