Generic competition on the horizon as many pharmaceutical companies face patent expirations

The impact of generic drugs-which now account for more than 70% of all prescriptions dispensed in the United States-will continue to increase as some of the world’s most-prescribed products lose their patent protection in 2011 and begin facing generic competition.

Among the brand names facing the end of market exclusivity this year are Lipitor (Pfizer), Plavix (Bristol-Myers Squibb/Sanofi Pharmaceuticals), Zyprexa (Eli Lilly), and Levaquin (Ortho-McNeil). Together, these drugs accounted for more than 93 million prescriptions dispensed and generated more than $17 billion in total sales during the past 12 months, according to IMS Health.

The full impact of patients shifting to lower-cost generic alternatives for these products, as well as other brands in their therapy classes, mostly will be felt in 2012, because the timing and expected competitive intensity among generic entrants, IMS noted.

In 2011, generic competition in the United States is expected to dampen sales for about $30 billion worth of drugs facing patent and exclusivity cliffs, according to reports from IMS and Credit Suisse.