Two big drugs got generic competition in the U.S. this week. First, there's AstraZeneca's (NYSE: AZN) Arimidex treatment for breast cancer. Next, the Pfizer antidepressant Effexor XR. Together, the drugs accounted for almost $4 billion in U.S. sales.
It's not as if the rivalries come as a surprise; in Effexor XR's case, Wyeth (now Pfizer) has had a launch-date deal with Teva Pharmaceutical Industries since 2006. AstraZeneca has already said that generic competition for Arimidex--a $916.8 million seller--would hit its second-half figures. Generics makers are piling into the market with their versions, including Teva, Mylan and APP Pharmaceuticals.
Pfizer has a bit of a reprieve: Teva has 180 days of marketing exclusivity. Typically, drug prices don't drop much when just one generic competitor hits. The real pain comes six months later, when other companies launch their versions. Effexor's Q1 sales in 2011 will better predict the generics' impact.