As if drug companies did not have enough problems. Research productivity has dropped, patents on blockbusters are running out and regulators have slowed their approval of new drugs. Now, in the past year, US courts have become more sceptical of existing patents, making it much harder to stop generic manufacturers from launching competing drugs.

Last spring, an important appeals court made it easier to challenge drug patents on the grounds that their chemical formulas are obvious, and the US Supreme Court reinforced the message in a case involving automobile pedals. Drug manufacturers are vulnerable because they have been trying to extend drug life by patenting small changes, such as extended release formulations. Last Monday, a trial court tossed out Germany's Bayer's patent for its top-selling contraceptive on grounds of obviousness.