Eli Lilly has bagged an additional six months of patent protection in the USA for Cymbalta after the blockbuster met US Food and Drug Administration requirements for paediatric exclusivity.

The patent on Cymbalta (duloxetine), which is approved for depression, pain management and fibromyalgia, will now expire in December 2013 instead of June next year. However, the US major noted that paediatric exclusivity does not mean the drug is approved for use in children and added that "based on study results, Lilly will not be seeking a paediatric indication for Cymbalta".

Nevertheless, the extension is a boost for Lilly as Cymbalta is the firm's biggest earner. First-quarter sales rose 23% to over $1.11 billion, most of which comes from the USA, and the drug is driving growth as Lilly deals with the patent expiry on its former biggest-seller, the antipsychotic Zyprexa (olanzapine).