The US Food and drug Administration has approved a generic competitor to GlaxoSmithKline’s orally-disintegrating tablet formulation of Zofran (ondansetron), its nausea treatment for patients undergoing chemotherapy for cancer.

But launch of the generic, which was developed in the USA by Par Pharmaceuticals’ subsidiary Kali Laboratories under the term of a licensing agreement with Croatian drugmaker Pliva, will be delayed while litigation between Kali/Pliva and GSK plays out.

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.

Once cleared for sale by the courts, or by the expiry of GSK’s patents, the generic will be sold by Pliva Inc, the Croatian firm’s US subsidiary, which says it has 180 days’ exclusivity for the product under the USA’s first-to-file legislation. Profits will be split with Kali.