UCB will need to resolve issues concerning crystal formation before regulators in the USA approve the Belgian firm’s Neupro patch for Parkinson’s disease and restless legs syndrome.

The company noted that it has received a complete response letter from the US Food and Drug Administration for its Neupro (rotigotine transdermal system) patch to treat the signs and symptoms of advanced Parkinson's disease and moderate-to-severe primary RLS.

In the letter, the FDA concludes that there was “substantial evidence of effectiveness of Neupro” but UCB needs to first resolve the issue of crystal formation in the patches. The firm said it will now discuss the contents of the letter and the next steps to be taken with the agency.

The FDA accepted for filing supplemental New Drug Applications for the two indications in December last year and at that time, Neupro was available in the USA for early-stage idiopathic Parkinson's disease. However the company recalled Neupro in April after it was revealed that specific batches “had deviated from their approved specification”.

At the time, Iris Loew-Friedrich, chief medical officer of the firm, stressed the issue is “not one of product contamination or toxicity but rather one of possibly reduced clinical performance of some patches”.

UCB added that in Europe, “a complete cold-chain storage and distribution system”, implemented by September 2008, “has helped to control the crystal formation issue and allowed existing patients to continue their therapy”. Pending a decision by the European regulatory authorities, UCB aims to make Neupro available again here during the first half of 2009.