Shares in SkyePharma have slumped after regulators in the USA rejected the UK drug delivery specialist’s asthma drug Flutiform.

The company has received a complete response letter from the US Food and Drug Administration saying that it cannot approve the New Drug Application “in its present form” for Flutiform (fluticasone/formoterol. The agency has also raised a number of “substantive issues to be addressed”.

Tellingly, SkyePharma says “if undertaken”, the sticking points “would involve significant additional clinical work including work to provide the additional data on dosing as previously disclosed”. The FDA asked for “further clarification” concerning the treatment in April 2009 and again in September.

The London-headquartered company said “discussions will be sought with the FDA as soon as possible to determine what steps would need to be taken before the application can be approved”. Further information on “the impact of the additional work on timing and costs will be announced once clarification has been obtained”, SkyePharma added.

Trials do not come cheap and SkyePharma ended 2009 with cash and equivalents of £27 million. The firm insisted that the review issues are not expected to have an impact upon the development of Flutiform in Europe, where it remains on track to be filed sometime in this quarter, or in Japan, where Phase II studies should be completed this year.

Investors reacted badly to the news and SkyePharma shares ended the day down 12.7% at £0.84.