The Medicines and Healthcare products Regulatory Agency (MHRA) has issued advice for prescribers following the announcement last week by the European Medicines Agency (EMA) in relation to contamination of metformin medicines.
The EMA reported that trace amounts of the impurity, N-nitrosodimethylamine (NDMA), have been found in a small number of metformin diabetes medicines outside the EU. NDMA is classified as a probable human carcinogen on the basis of animal studies. It is present in some foods and water supplies, but it is not expected to cause harm when ingested in very low levels.
The agency advised that the levels of NDMA in the affected non-EU metformin medicines are very low and appear to be within or even below the range that people can be exposed to from other sources, including certain foods and water. At this point, there are no data indicating that EU metformin medicines are affected.
The MHRA says it is aware that NDMA has been found in some metformin medicines and is working closely with the EMA and other regulatory authorities to determine whether any further action is required. For now, the MHRA is advising that treatment with metformin should continue.
Metformin is the latest in a long line of medicines which have been found to be contaminated with NDMA and nitrosamines. Last year, NDMA and other impurities were found in sartan medicines. The EMA launched a review of the issue, which was later extended to include some ranitidine products.
A Dutch study reported last year that exposure to NDMA-contaminated medicines was associated with a small increase in risk for overall cancer (HR, 1.09; 95% CI, 0.85-1.41). The HR increased to 1.46 for colorectal cancer and 1.81 for uterine cancer, although confidence intervals were wide.
