Regulators in the USA have again delayed a decision on approval of an extended-release version of GlaxoSmithKline’s Parkinson’s disease drug Requip.

The US Food and Drug Administration has extended the Prescription Drug User Fee Act action date for Requip (ropinirole) XL, saying it needs more time to review new data. A decision, due in the first quarter, is not now expected until the second quarter of 2008.

Specifically, following the receipt of an approvable letter for Requip XL issued in December, GSK has recently submitted additional information on food effect to the FDA. The agency says it would not have sufficient time to review said information prior to the original action date even though it has not requested any new clinical data.

This latest delay led to a slight dip in GSK shares but was more damaging to shares in SkyePharma, the UK firm which licensed the Geomatrix technology used in the extended-release version of Requip. Requip XL is already approved in 13 European countries including a launch in France only last week. The original formulation of Requip is already approved for both Parkinson’s and restless leg syndrome.