Everyone -- including my Foolish colleague Ryan Fuhrmann, our friendly Pfizer (NYSE:PFE) bull -- has zeroed in on the upcoming Lipitor patent expiration as the source of the company's woes. But Pfizer's situation is actually even more daunting, if possible, than just facing generic competition on the world's best-selling drug. Drugs like Norvasc and Zyrtec, with $4.9 billion and $1.6 billion in sales, respectively, will also be losing U.S. patent protection this year. These two drugs accounted for 13% of the company's revenue last year. All you have to do is scroll down to page nine of its latest 10-K filing concerning "patent expirations" to see some of the blockbuster drugs and associated billions in sales that will be lost over the coming years.

The cost-cutting that Pfizer is undertaking to drive stronger profitability can only go so far. And doing things like cutting its sales and marketing force does have tangible effects on its business, like slowing down sales growth even further.

As our Pfizer bull has stated, the outlook for Pfizer is cloudy past 2008. The earnings-shortfall storm in the future may be even worse than expected. Some of the drugs Pfizer has just launched, like Exubera and Sutent, which are supposed to pick up the slack for the other compounds going off patent, may face tougher competition or get off to a much slower marketing launch than expected.

Faith is nice in terms of religion, but when it comes to my investments, I'd like to be able to make some reasonable assumptions about future growth plans. With Pfizer, the only way to envision bottom-line growth beyond the 2010 Lipitor patent expiration is to take it on faith. Unless the valuation becomes much more compelling or Pfizer better outlines how it will use its cash hoard, I think I'll pass.

Think you're done with this Duel? You're not! Go back and read the other three arguments, then vote for a winner.

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Fool contributor Brian Lawler does not own shares of any company mentioned in this article. The Fool has a disclosure policy.