Apotex wins latest round in generic paxil litigation

You have full access to this article via your institution. Download PDF In the ongoing litigation over Apotex's generic version of GlaxoSmithKline's (GSK) antidepressant paroxetine

hydrochloride (Paxil), the US Federal Circuit Appeals Court has reversed the previous patent infringement ruling of the district court against Apotex, but at the same time has found

GSK's US patent 4,721,723 invalid, thereby ultimately handing a victory to Apotex. In the 1970s, paroxetine hydrochloride (PHC) anhydrates were invented in the UK and, in 1998, a PHC

hemihydrate compound was patented by GSK (then SmithKline Beecham) and marketed as Paxil. In 1998, Apotex submitted an Abbreviated New Drug Application to the US FDA to market an

antidepressant based on the anhydrate form of PHC, and filed a certification that its proposed product would not infringe GSK's '723 patent for the PHC hemihydrate product.

However, GSK claimed that Apotex's anhydrate version naturally converts into the hemihydrate version, making it likely that there would be some hemihydrate in Apotex's product,

therefore infringing the '723 patent. Although the district court interpreted the claim as requiring the presence of commercially significant amounts of the hemihydrate for infringement

to take place, the Federal Court found no reason to limit the scope in such a way. The public use of an invention more than one year prior to its patent application date prevents the

inventor from obtaining a US patent. However, the doctrine of experimental use allows an inventor to engage in activities that would otherwise fall under the public use bar. Judge Rader, for

the majority, found that patent '723 was invalid because clinical trials occurred more than one year prior to filing; furthermore, the experimental use exemption did not apply in this

case because the trials tested only the safety and efficacy of PHC hemihydrate as an antidepressant rather than experimental use of the chemical compound as claimed in claim 1. REFERENCES *

SmithKline Beecham versus Apotex: http://www.fedcir.gov/opinions/03-1285.doc Download references RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Apotex

wins latest round in generic Paxil litigation. _Nat Rev Drug Discov_ 3, 468 (2004). https://doi.org/10.1038/nrd1423 Download citation * Issue Date: June 2004 * DOI:

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