Eli Lilly (NYSE: LLY) is getting a little taste of its impending patent cliff a little early. A patent cut bank, if you will.

Rather than losing it the old-fashioned way -- by watching the patent expire -- Eli Lilly is losing the patent on attention-deficit-disorder drug Strattera because a court found the patent that's set to expire in 2017 is invalid. Eli Lilly plans to appeal the decision, but thinks that generic-drug makers will launch copycat versions of the drug in the meantime. Eight drugmakers already have tentative Food and Drug Administration approval for a generic version, including Teva Pharmaceutical (Nasdaq: TEVA), Mylan (Nasdaq: MYL), Novartis (NYSE: NVS), and Dr. Reddy's Laboratories (NYSE: RDY).

The drug had sales of almost $300 million during the first half of the year. That's not quite a blockbuster, but Lilly isn't that large of a company; Strattera accounted for 2.6% of revenue over that time. Lilly lowered its revenue guidance for the year, but thinks it'll be able to make its earnings guidance through a series of cost cuts.

Cost cuts aren't going to be enough when the full patent cliff hits, starting with multibillion dollar Zyprexa in 2011 and potentially Gemzar even earlier, if the company can't get another recent patent loss overturned.

Essentially, Eli Lilly is a walking time bomb. Much of the revenue explosion is already priced in -- Eli Lilly trades at just eight times the middle of this year's adjusted earnings guidance and has a whopping 5.4% dividend -- but investors are counting on the pipeline to grow revenue after the cut bank turns into a cliff. In the long term, that might be an OK strategy, considering how many early-stage compounds Eli Lilly has in its pipeline, but for the short term, it may leave investors up a creek without a paddle.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. Novartis and Dr. Reddy's Laboratories are Motley Fool Global Gains selections. The Fool's disclosure policy prefers exploding metaphors to those involving water.