Meanwhile, Merck has a patent fight of its own going on. Their osteoporosis drug Fosamax (alendronate) is being targeted by Teva and Barr, but Merck (not surprisingly) has been filing suits against both of them over the last few months. The Barr lawsuits are in New York, Teva's is in Delaware, and we might see some decision on them in the next couple of months.
Merck doesn't seem to be arguing the point about composition-of-matter. What they're claiming is that they have patents covering the entire methods of treatment for bone resorption. These patents have expiration dates all the way out to 2018, which is a date that they can live with. After then, they say, you can do anything you want with alendronate. It's not clear what other sorts of compounds might fall under these treatment claims, but I haven't heard of any other companies that feel that they have a stake in this fight.
This is yet another test of the whole method-of-treatment patent idea. It's complicated in this case, because there are nine Merck patents involved, and they have all sorts of claims among them: chemical matter, processes for preparation, medical treatment, and who knows what else. I've looked into them a bit, but my head starts to pound a bit after about five or six patents in a row. Gets me right up around the eyebrows. . .but I digress.
There are plenty of compound-specific claims, of the sort that read "A method for treating diseases involving bone resorption, which comprises administering to a patient in need thereof a therapeutically effective dose of a compound of claim #. . ." Many of these don't seem to be for alendronate-type compounds, since this is the sort of claim that usually refers back to some novel chemical matter (which is the real subject of the particular patent.) But a closer reading would, I'm sure, find some that refer to alendronate itself, because these cases would have been decided already if there weren't some meat on the bones. [Note added 9/4: I edited this paragraph from its original version last night, which made even less sense.]
Barr and Teva say, as you'd expect them to, that the Merck patents are invalid and/or unenforceable. Unraveling all this won't be fun, and no doubt whatever verdict comes down will be immediately appealed. "Where it will all end, knows God" as the old New Yorker parody of Time magazine had it.
These sorts of court battles are routine, and it's easy to see why. While they go on, the status quo is preserved. The challenging generic company has its hands tied. As long as the drug brings in more money than you pay in legal fees, then you're ahead of the game.