Teva Pharmaceutical Industries became the first company in the USA to launch a generic version of GlaxoSmithKline’s Zofran Injection this week, although others are expected to follow suit shortly after the drugmaker waived a patent extension for the product.

Ondansetron is indicated for the prevention of nausea and vomiting associated with initial and repeat courses of emetogenic cancer chemotherapy and prevention of postoperative nausea and vomiting, according to the FDA.

According to the online magazine Drug Topics, Zofran was the 20th most expensive brand-name drug used in hospitals in the USA in 2005, with total costs of approximately $840 million.

"These approvals will result in significant savings for the American public," commented Gary Buehler, director of the Office of Generic Drugs in the USA. Another injectable version of the drug, from Baxter, has also received tentative approval from the agency.

However, the battle for generic versions of the oral formulations of Zofran has yet to be decided. Earlier this month Canadian generics company Apotex filed a lawsuit against the US Food and Drug Administration trying to block any rival company from getting six-months’ exclusivity for Zofran tablets under the first-to-file legislation in the USA.

India’s Dr Reddy’s Laboratories is thought to be in pole position for securing exclusivity on Zofran tablets.

Earlier this year, GSK blocked generic competition to a quick-dissolving formulation of the drug, Zofran ODT, that is due to see its US patent protection expire on December 24.