* naproxcinod talks may not conclude until H1 2010
* NicOx shares close down 7.4 percent
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PARIS, June 18 (Reuters) - Shares in NicOx slumped on Thursday after the French biotech firm said talks to seal a partnership to bring anti-inflammatory drug naproxcinod to market may not reach a conclusion until the first half of 2010.
Shares in NicOx closed down 7.4 percent at 8.88 euros, compared to a 1 percent rise in France's CAC 40 index.
Some of NicOx's potential partners prefer to wait until they see the drug's guidelines, which are being negotiated with health authorities, before signing a commercial partnership with NicOx, a spokesman said.
The main question is whether the U.S. Food and Drug Administration will let NicOx state on the label that the drug is less likely to increase arterial pressure than other competing medicines, the spokesman said.
Negotiations over the medicine's guidelines will take place during the first half of 2010, he added.
He confirmed that NicOx is likely to clinch two or three partnerships depending on the geographical zone, adding that partners will include global, regional and specialised pharmaceutical firms.
The submission for marketing approval will still be sent to the FDA this summer as expected, the spokesman said, adding that a proposal will be sent to European health authorities two to three months after the United States.
NicOx has high hopes for naproxcinod, which took 10 years to develop at a cost of around 100 million euros ($139.6 million). It would be its first marketed drug and the only branded rival to Pfizer's Celebrex, which made $2.5 billion in sales last year. ($1=.7165 Euro) (Reporting by Juliette Rouillon and Sophie Taylor; editing by Elaine Hardcastle)