Teva Cleared to Sell Generic Effexor XR -- a Pfizer Blockbuster

Teva Pharmaceutical Industries (TEVA) said Tuesday that the U.S. Food and Drug Administration approved its generic version of Pfizer's (PFE) antidepressant Effexor XR, or Venlafaxine.

Teva said that shipment is expected to commence on July 1, 2010, as per the terms of the 2006 agreement with Wyeth, which Pfizer acquired last year. According to the agreement, Teva agreed with Wyeth not to sell its version until July 1, 2010.

Teva, being the first company to file for a generic application, will have a 180-day period of marketing exclusivity, meaning no other generic company will be allowed to sell its product during that time. This is the period when Isreal-based Teva will make the bulk of the profit from its generic version.

This illustrates exactly what's meant when analysts and investors talk about "patent cliff." Teva said that according to IMS sales data, the branded drug had annual sales of approximately $2.75 billion in the U.S. Pfizer will now lose most of it as many will shift to the much cheaper generic version by Teva.

Teva shares were flat in premarket trading, while Pfizer's fell nearly 1%.