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Generic threat to Lilly's biggest seller

Published on 03/11/03 at 03:04pm

A court challenge to Eli Lilly's patent on its number one drug Zyprexa could spell serious trouble for the company, still recovering from a generic onslaught against former blockbuster Prozac.

Generics manufacturer Ivax is claiming that Lilly withheld information from clinical studies when filing for schizophrenia treatment Zyprexa's patent, a claim UBS Warburg analysts believe could be more serious than first suspected.

The court case alleges Lilly engaged in "inequitable conduct" in order to gain Zyprexa's central patent, which is currently due to expire in 2011.

Ivax claims that Lilly withheld data from a study carried out on dogs to bolster its case for the patent being different to that of 222, another compound Lilly had already patented.

Study results Lilly submitted to the US patent office focused on just 8 of the 40 dogs actually used to compare Zyprexa and 222, according to UBS Warburg.

Lilly says Ivax's claim has a huge burden of proof. Lilly's general counsel Bob Armitage told the Financial Times: "Proving the claim of inequitable conduct is like winning the lottery, and the court is not looking to encourage frivolous claims of inequitable conduct."

In the fourth quarter 2002 Zyprexa's $989 million sales, up 10% from 2001, accounted for a third of Lilly total pharmaceutical sales.

Lilly is vigorously defending Zyprexa patent against other challengers. The company is currently suing Indian generics manufacturer Dr Reddy's Laboratories to block US approval of that company's version of Zyprexa and last year took similar action against Israeli firm Teva.

Lilly is still suffering the after-effects of the end of patent protection for Prozac, previously its best-selling product. Sales of Prozac fell by 63% last year after it came off patent.

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