Adolor Corp’s delight that US regulators have lifted its clinical hold on expanding development of its recently-approved bowel drug Entereg has been tempered by the news that partner GlaxoSmithKline is thinking of terminating a part of the firms’ alliance.

Entereg (alvimopan) was finally approved in May by the US Food and Drug Administration to treat post-operative ileus (POI), helping patients regain gastrointestinal function earlier following bowel resection surgery. However the agency has now also decided to lift the clinical hold put on the drug last year for another bowel disorder, namely chronic opioid bowel dysfunction (OBD). Trials had been halted because of long-term concerns of heart attack.

Adolor chief executive Michael Dougherty said that "after a productive meeting and dialogue with FDA, we are very pleased to see the clinical hold lifted." He added that “there remains a large, unmet need for treatment options for the many patients suffering from this debilitating condition”.

However the US firm raised a few eyebrows by noting that “GSK is evaluating all options relating to the OBD programme, including whether to proceed with its involvement”. This relates to the companies’ initial agreement, signed in April 2002, which allows the UK drug major to end its involvement with Entereg as a treatment for OIC but still retain rights to the drug for the POI indication.

Mr Dougherty said that “should GSK determine to discontinue their involvement with the OBD programme, Adolor would expect to submit for review by FDA a protocol for an additional study in this indication”.

Entereg for POI has only been on the market for less than a month and access is limited to registered hospitals which have signed up to Adolor and GSK’s risk management programme. It is initially only available for short-term use.