The U.S. Food and Drug Administration said on Tuesday that some samples of sitagliptin, a compound of Merck’s ( MRK.N ) diabetes drug Januvia, were contaminated with a possible carcinogen.
The agency said it would not object to the temporary distribution of impurity-containing sitagliptin above the acceptable consumption limit to avoid shortages.
Shares of Merck, which was not available for comment, fell sharply before recovering to rise 0.8% to $89.27.
Sales of Januvia and the related combination drug Janumet totaled $1.23 billion in the second quarter.
The impurity Nitroso-STG-19, also known as NTTP, belongs to a class of nitrosamine compounds, some of which are classified as probable or possible human carcinogens based on laboratory tests, the agency said.
Agency scientists estimated the risk of NTTP exposure at intermediate tolerable intake levels of up to 246.7 nanograms per day and determined that this is a minimal additional cancer risk compared to lifetime exposure to NTTP at 37 nanograms per day.