Merck & Co has been rapped over the knuckles after failing to notify the US Food and Drug Administration about a change to its production and quality process for the leukaemia drug Elspar (asparaginase). In a letter to the company, the FDA said “this is a significant departure from your biologics license application an requires the submission of a prior approval document.”

Following a February inspection of its Pennsylvania facility, Merck was found to have been using a pre-existing cell culture rather than the ‘master’ cell culture to manufacture Elspar. In addition, the company implemented another manufacturing process for selecting cells, which the FDA stated “amounts to re-cloning and requires the submission of a prior approval supplement.”

The letter, dated July 22, was posted on the agency’s website yesterday. Merck has 15 days to comply with the FDA’s requests or will face further regulatory action.