Drug firms show innovation in dealing with patent expiry

Four of the USA's top 10 best-selling prescription drugs face patent expiry this year, providing, at least in theory, an unprecedented window of opportunity for generic drugmakers. However, the emergence of "authorized generics" (Marketletter July 10) and the rise in "citizen petitions" lodged against generic drug applications by research-based drug firms (Marketletter July 17) have led supporters of generic drugs to cry foul, according to the Chicago Tribune newspaper.

The scale of patent expiry is likely to offer opportunities for generic manufacturers: the Chicago Tribune lists 16 drugs that totalled almost $30.0 billion in sales for 2005, but which face generic competition by 2010 at the latest.

The list, compiled from data provided by Express Scripts (showing 2005 sales data for the US market), included: US drugmaker TAP Pharmaceutical's Prevacid (lansoprazole/amoxicillin/clarithromycin; $3.3 billion, expiring in 2009); US drug major Merck & Co's Zocor (simvastatin; $3.1 billion, which expired recently), Fosamax (alendronate; $1.5 billion, expiring in 2008) and Cozaar/Hyzaar (losartan/losartan plus hydrochlorothiazide; $1.0 billion, expiring in 2010). UK-based GlaxoSmithKline loses Advair (fluticasone propionate/salmeterol; $2.8 billion, expiring in 2008) and Flonase (fluticasone propionate; $1.0 billion, expiring this year). Global behemoth Pfizer loses patents on Zoloft (sertraline HCl; $2.6 billion, expiring this year), Norvasc (amlodipine; $2.0 billion, expiring next year) and Zyrtec (cetirizine HCl; $1.4 billion, expiring in 2008). US drug major Wyeth loses Effexor/XR (venlafaxine; $2.2 billion) in 2008 and France's Sanofi-Aventis loses Stilnox/Ambien (zolpidem; partnered with Japan's Fujisawa; $1.9 billion) in 2007.