Simply put - the reasons include patent expirations; modest pipelines; slowing FDA approvals; balance sheet strength has peaked; and lingering uncertainty over biogenerics, reimportation and Medicare Part D talks. Moody’s actually publicized its view - which went to negative from stable - earlier this month, but today issued its full report.

Unfortunately, we’re prevented from providing a link, but we did chat briefly with Moody’s Michael Levesque, a senior vp and pharma analyst, who says there are a few bright spots. “We’re not projecting a doomsday scenario by any means. It’s still a profitable industry with demographics in its favor. And absent patent expirations, most of the biggest drugs are still growing from volume trends and price increases, and the industry is still generating a lot of cash flow. But there were very high credit ratings for years, and now there’s pressure ahead. So those ratings may come down a bit.” Pfizer, by the way, was the only big US drugmaker that, on an individual basis, received a lowered outlook.

As an example, the chart details patent expirations facing a five big US drugmakers between 2010 and 2012 (you may want to click on the chart for greater detail). Large drugs subject to generic competition in this time frame include Pfizer’s Lipitor, Bristol-Myers Squibb’s Plavix, Eli Lilly’s Zyprexa, Merck’s Cozaar and Wyeth’s Effexor XR. Based on current revenues, Moody’s believes that these drugmakers will face generic competition on products that currently represent over 45 percent of their existing revenues