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Merck: "about" means "exactly"

Merck's recent string of bad news was extended by last Friday's ruling by the Federal Circuit invalidating its patent on once-a-week Fosamax:

Merck received yet another blow yesterday when a federal appeals court unexpectedly invalidated a patent on Fosamax, an osteoporosis treatment that is Merck's second-best-selling drug.

. . . The decision reverses an August 2003 ruling in Federal District Court in Delaware that upheld a patent on a once-a-week formulation of Fosamax. The patent on Fosamax in its original daily dosage expires in 2008. The vast majority of patients take the weekly dose, whose patent protection had been expected to last until 2018. Yesterday's decision means Merck could face generic competition for both the daily and the weekly versions of Fosamax as early as February 2008.

The main issue in the case, Merck v. Teva Pharmaceuticals (2005 WL 181711), was whether Merck's patent on once-weekly Fosamax was invalid as obvious. An interesting subsidiary issue was whether Merck had successfully redefined the word "about" in its specification. Merck's argument was that when the claim used the words "about 35 mg" of alendronic acid, it really meant "exactly" 35 mg.

The CAFC rejected this argument, but it's not as patently absurd as it first seems (please forgive the pun). A patentee is "its own lexicographer," meaning it can define the terms in its claims however it wants. Merck argued that it wasn't just redefining the word "about." Instead, it defined the entire phrase "about 70 mg of alendronate monosodium trihydrate, on an alendronic acid basis" to mean "whatever amount of total compound is necessary to provide exactly 70 mg of alendronic acid."

The case may still have come out against Merck even if it had won this claim-construction argument, but the argument is still pretty fierce. There's a vigorous dissent from Judge Rader about the claim construction issue, and about the issue of Fed. Cir. deference to trial courts. If you're a patent law junkie, it makes for good reading.