In the wait for patent expirations, what's in store for Eli Lilly?

The biggest nightmare for pharmaceuticals is when their drug patent expires. Patent expiration is daunting for any branded pharmaceutical as it leaves the door wide open for generic versions of the company's drug which have a direct impact on the revenue stream this drug brings to the patented drug manufacturer, comments South Africa-based independent analyst Rothman Research.

Branded drug production normally involves huge investments in R&D from companies like US drug major Eli Lilly) and the success of the drugs is very often a gamble. However, a successful propriety drug which meets all of the US Food and Drug Administration's criteria can be a virtual gold mine for the company. An example is Eli Lilly's best-selling drug Zyprexa (olanzapine), used in the treatment of schizophrenia and other psychological disorders, which contributed to about 23% of the company's sales in 2009 and which will expire in 2011.

Five of Lilly's best-sellers facing patent loss up to 2017