UK drugmaker ProStrakan said last week that regulators across the pond have again requested additional clinical trial data for its pain drug Rectogesic, further delaying a potential US launch.

The Galashiels, UK-based group confirmed that it has received a complete response letter from the US Food and Drug Administration in response to its New Drug Application for Rectogesic (nitroglycerin ointment), outlining certain issues that need to be addressed before it can take another look at its request to market the drug for pain associated with chronic anal fissures.

This is not the first time the drug has been hit by a setback in the US; an earlier review of Rectogesic by the FDA resulted in an “approvable” letter asking ProStrakan to perform an extra trial in patients to confirm the drug’s efficacy, resulting in a re-submission of the NDA for the drug in September last year.

Still, this latest delay seems to have come as no surprise to the drugmaker. “It was always possible that further data may be required for a US approval,” explained Wilson Totten, the company’s chief executive, and he said with this in mind the group had not committed to commercialising Rectogesic in the US either itself or through partners, and that it had not made any projections for US sales in its internal budgets.

“However, the unmet medical need in the US for a prescription medicine for treating chronic anal fissure pain remains, and ProStrakan will evaluate viable future paths for Rectogesic in the US”, Totten stressed.

Shareholders seemed relatively unmoved by the news, perhaps because the group remains confident of making good progress elsewhere in its US strategy. Abstral, a new, sub-lingual formulation of fentanyl is currently awaiting FDA approval for breakthrough cancer pain, and Fortesta, a testosterone replacement therapy for male hypogonadism, is expected to be re-filed by partner Endo Pharmaceuticals in mid 2010.

As for Rectogesic, ProStrakan said it intends to meet with the FDA in the near future to discuss its requirements in more detail.