All eyes will likely be tuned to Eli Lilly later on today when a US district judge is expected to issue his long-awaited ruling on a challenge to the patent covering its top-selling anti-psychotic, Zyprexa (olanzapine).

The Zyprexa trial began last, with Ivax’ subsidiary, Zenith Goldline, alleging that Lilly had “double patented” the product [[28/01/04d]], and seeking to have a patent covering the drug until 2011 invalidated, claiming that the so-called double patenting contravenes patent rules. At the time, a spokesman for Lilly told PharmaTimes News Online that an original patent, which was issued in 1978 and expired in 1995, covered the genus of compounds to which Zyprexa belongs, while a separate compound patent specifically covers the multi-dollar drug until 2011.

Although Lilly continues to remain confident that Zyprexa’s compound patent is valid and the generic manufacturers’ claims are without merit, and expects to prevail in the case, it said that “an unfavorable outcome would have a material adverse impact on the company’s consolidated results of operations, liquidity, and financial position.”

Zyprexa remains one of Lilly’s best-selling drugs with 2004 sales topping $4.4 billion dollars – however, this was just 3% higher than the figure recorded in 2003, primarily as a result of heightened competition in the US market, where sales slid by 8% [[27/01/05a]].