Shire of the UK got the green light yesterday evening for the first skin patch for treating attention deficit hyperactivity disorder from the US Food and Drug Administration (FDA).

The patch, called Daytrana (methylphenidate) has been approved for use in children aged six to 12 with ADHD and is the first alternative to oral medications for the estimated 2.5 million children with the condition in the USA. Shire said it hopes to launch the new product in the first half of this year.

For Shire, the approval boosts an ADHD treatment franchise that is already the company’s top earner, with its Adderall and Adderall XR (mixed amphetamine salts) oral formulations accounting for around half its $1.6 billion in revenues last year.

But Shire is battling to defend Adderall XR – its most important product with 2005 sales of $730 million – from generic challenges in the USA. Lawsuits are ongoing against two challengers, Teva and Barr Laboratories, while Shire has negotiated a settlement with Impax Laboratories to keep its copycat version off the market until 2010.

Daytrana is one of six new products Shire is hoping to launch in 2006 to guard against a possible loss of marketing exclusivity for Adderall XR. Another treatment for ADHD, New River Pharmaceuticals' NRP104, was submitted for approval in the USA at the end of 2005. Shire has co-promotion rights to this product in the USA and excusive marketing rights elsewhere.

US approval of Daytrana is also a boost to drug delivery specialist Noven Pharmaceuticals, which developed the transdermal formulation used in the product. Noven is due to receive a $50 million milestone payment from Shire on US approval, as well as additional milestone payments of up to $75 million depending on the level of Shire's commercial sales of the product.

Shire said Daytana would carry a warning about skin sensitisation reactions, which were debated at an FDA advisory committee on the product in December 2005, as well as other warnings that are applied to all ADHD drugs. The FDA has convened two recent advisory committee meetings to discuss adding tighter warnings to the labelling of these drugs, particularly with regard to cardiovascular and central nervous system side effects.

- Meanwhile, there was somewhat worse news for Shire yesterday after it emerged a second company, CorePharma, had filed for approval in the USA for a generic version of its extended-release Carbatrol (carbamazepine) product for the treatment of epilepsy and trigeminal neuralgia. The UK firm has already seen this product challenged by Nostrum Pharmaceuticals in the USA, and has filed a patent infringement lawsuit to block approval.