GlaxoSmithKline has won a reprieve in its bid to block generic competition to a quick-dissolving formulation of its nausea drug Zofran (ondansetron) in the USA.

The US Food and Drug Administration (FDA) said yesterday it had rescinded an approval granted on November 18 for a generic version of Zofran ODT made by Kali Laboratories, a unit of Par Pharmaceutical, which licenses the product from Croatian pharmaceutical company Pliva.

The approval was retracted after a US District Court in New Jersey ruled that the FDA’s go-ahead for the generic infringed a patent held by GSK that is not due to expire until December 24, 2006.

Zofran ODT was launched in the USA in 1999 and had sales of around $225 million dollars in 2004. GSK won a lawsuit earlier this year backing its patent estate for Zofran ODT, blocking generic launches until December 2006.