GLAXOSMITHKLINE, the pharmaceutical group, has won a significant battle in its war to protect its business from makers of generic drugs after a US judge upheld a patent for Zofran.

Judge Jose Linares, of the District Court of New Jersey, upheld a so-called “method of use” patent covering the way that the active ingredient in Zofran works. The judge found that a copycat rival under development by Kali Laboratories, now part of Par Pharmaceuticals, would infringe GSK’s intellectual property rights.

The drug, which is used to treat nausea in patients undergoing chemotherapy, has sales of £750 million a year. Generic manufacturers have targeted bestselling drugs under the method-of-use patent because it is difficult to protect the way chemicals act with the body.

J.P. Garnier, GSK’s chief executive, said that the victory signalled a swing back to rational thinking. He said: “Judges are beginning to realise that generic manufacturers do not conduct meaningful research in the laboratory, only in the library. This is a really, really important victory.” The company now expects Judge Linares to uphold its Zofran patents in a second case, against Dr Reddy’s Laboratories.

News of the court victory came as GSK unveiled second-quarter results that beat forecasts, despite manufacturing problems at a plant in Puerto Rico. Second-quarter sales rose 6 per cent to £5.2 billion, lifting pre-tax profits by 9 per cent to £1.6 billion.

Dr Garnier said sales of Paxil CR, a treatment for depression, and Avandamet, for diabetics, had recovered by almost 50 per cent since the drug maker was allowed to resume manufacture. US regulators stopped production for four months earlier this year after discovering faults in the manufacturing process. Dr Garnier added that he expected sales to return to normal in a matter of weeks.

He said future growth would come from GSK’s late-stage drug pipeline. The group had also been able to report positive data on 11 of 15 programmes scheduled for late-stage testing this year. Dr Garnier added that of the remaining four, the outlook for just one, a multiple sclerosis treatment, was out of the company’s hands. “So far this year, we have not had a single drug fail on us because of concerns over toxicity,” he said.

Dr Garnier said that he expected about half a dozen experimental drugs to enter final tests this year. “We are very, very happy about the progress of our pipeline,” he said.

The shares rose 12p to £13.40 as Dr Garnier said that he expected double-digit earnings per share growth for the year.

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