Salix Pharmaceuticals is going to have to wait a fair bit longer to get a final decision from US regulators for its diarrhoea drug crofelemer.

The US Food and Drug Administration has told the company that its New Drug Application for crofelemer for the symptomatic relief of non-infectious diarrhoea in patients with HIV/AIDS on anti-retroviral therapy, is still under review. As such, it has missed the scheduled Prescription Drug User Fee Act (PDUFA) goal date of September 5.

Salix chief development officer Bill Forbes noted that “the primary topic is the production and control of the crofelemer active pharmaceutical ingredient, a complex mixture that is the first botanical product to be reviewed by the agency for oral use". He said the company and the FDA are committed to "a robust level of cooperation and data exchange", adding that "our efforts to date have advanced both the chemical and the regulatory science methods available to ensure the quality and clinical usefulness of crofelemer and, potentially, other botanical products".

Crofelemer acts by blocking chloride ion channel secretion and accompanying high volume water loss in diarrhoea. It is isolated and purified from a tree found in the Amazon basin, Croton lechleri, also known as dragon's blood.

Salix now expects a final decision on its New Drug Application for crofelemer by the end of the first quarter of 2013.