substantial revenue declines occur in the first year after patent expiration. Revenues in many international markets do not have the same sharp decline compared to the U.S. in the first year after loss of exclusivity, due to less restrictive policies on generic substitution, different competitive dynamics, and less intervention by government/payers in physician decision-making, among other factors.

• The loss of patent protection with respect to any of our major products can have a material adverse effect on future revenues and our results of operations. As mentioned above, our performance in 2008 was significantly impacted by our loss of U.S. exclusivity for Norvasc in March 2007 and Camptosar in February 2008. Further, we experienced a substantial adverse impact on our 2008 performance from the loss of U.S. exclusivity for Zyrtec/Zyrtec D in late January 2008, at which time we ceased selling this product. These three products represented 6% of our total revenues and 1% of our total U.S. revenues for the year ended December 31, 2008, and 11% of our total revenues and 12% of our total U.S. revenues for the year ended December 31, 2007. Revenues in the U.S. contributed approximately 42% of our total revenues in 2008, 48% of our total revenues in 2007 and 53% of our total revenues in 2006.

• Patents covering our products are also subject to legal challenges. Increasingly, generic pharmaceutical manufacturers are launching products that are under legal challenge for patent infringement before the final resolution of the associated legal proceedings—called an “at-risk” launch. The success of any of these “at-risk” challenges could significantly impact our revenues and results of operations. Generic manufacturers are also advancing increasingly novel interpretations of patent law to establish grounds for legal challenges to branded patents.

• There is a continuing disparity in the recognition and enforcement of intellectual property rights among countries worldwide. Organizations such as the World Trade Organization (WTO), under the WTO Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS), have been instrumental in educating governments about the long-term benefits of strong patent laws. However, certain activists have challenged the pharmaceutical industry’s position in developing markets.

• The integrity of our products is subject to an increasingly predatory atmosphere, as seen in the growing problem of counterfeit drugs. These drugs can harm patients through a lack of active ingredients, the inclusion of harmful components or improper accompanying packaging. Our ability to work with law enforcement to successfully counter these dangerous criminal activities will have an impact on our revenues and results of operations.

Our response:

• We will continue to aggressively defend our patent rights against increasingly aggressive infringement whenever appropriate. (See also

Notes to Consolidated Financial Statements—Note 19. Legal Proceedings and Contingencies).

• We will continue to participate in the generics market for our products, whenever appropriate, once they lose exclusivity.

• We will continue to take actions