High Court strikes down Merck's patent on alendronate

Two patents held by pharmaceutical giant Merck for the drug alendronate (Fosamax) have been struck down in the British High Court, leaving the field clear for manufacturers of generic drugs. Alendronate is used in the treatment of osteoporosis and Paget's disease.

The lawsuit was filed by Israeli generic drug manufacturer Teva Pharmaceutical Industries and the British companies Arrow Generics and Generics (UK). They sought revocation of two Merck patents in the United Kingdom: the original 1982 patent covering alendronate's use for osteoporosis and a 1997 patent covering a high dose, once weekly formulation.

The plaintiffs argued that the idea of using alendronate to treat bone loss was obvious to any professional in the field, given the research of Professor Herbert Fleisch's group in Switzerland in the late 1960s. They also said that the later patent, covering the weekly formulation, was an obvious development of an existing product, rather than an original therapeutic idea. Obviousness is a standard legal argument against patent exclusivity.

Professor Fleisch's group did not develop alendronate but a precursor compound, pyrophosphonate, which lacked in vitro efficacy. Mr Justice Jacob of the High Court of Justice Chancery Division Patents Court accepted, however, that the knowledge developed by the group's research suggested an obvious possibility that study of the bisphosphonate compounds would likely yield drugs that were more effective. Alendronate was such a compound.

Mr Justice Jacob also accepted that the 1997 patent on once weekly alendronate was an obvious development. Holding both patents invalid, he said: “I do so with some regret. Merck have only had a few years' exclusive exploitation of alendronate. They must surely have had to make a very considerable investment and incurred considerable risk in bringing it to market. And mankind is better off as a result.

“But the patent system does not confer monopolies on those who develop obvious or old products, even if they have never been exploited. A workable system for that might be a good idea, particularly in the field of medicine and analogous fields.”

Merck said it would seek leave to appeal the decision. Sales of alendronate were worth about $2bn (£1.2bn; €1.8bn) in 2002. About 75% of sales are in the United States, where a court upheld the Merck patent in November, giving the company protection until 2007. About $70m of sales came from the United Kingdom.

Teva, one of the world's largest makers of generic drugs, still has to pass regulatory hurdles before it can sell alendronate in the United Kingdom. It expects to bring its generic version to the UK market in 2004.