US FDA finds potential carcinogen in popular diabetes drug

A carcinogenic substance called nitrosamine was found in higher-than-allowed levels in the samples of a popular diabetes drug, sitagliptin. The US Food and Drug Administration has allowed the drugs to be further sold and distributed to avoid shortages.

Three drugs that contain sitagliptin - Januvia, Janumet, and Steglujan were found to have NTTP belonging to the nitrosamine class of compounds.

The US has a high number of diabetes patients. With diabetes mortality rising across all races and income groups, the disease is epidemic in the country. According to the data collected in 2019, 37.3 million Americans (11.3% of the population) had diabetes and 8.5 million of them were undiagnosed.

Pharmaceutical company Merck & Co. has confirmed that recently detected a nitrosamine identified as NTTP in some batches of their sitagliptin-containing medicines. It added that the levels of the potentially cancer-causing compound were too low to be measured in a related extended-release therapy, reported Bloomberg. The company is working with health authorities to implement quality controls.

FDA said there is no data available to directly evaluate the carcinogenic potential of NTTP. The agency has used the information available to calculate a lifetime exposure limit for the compound.

Januvia is Merck's third best-selling drug with $3.3 billion in sales in 2021. Sitagliptin is used to control high blood sugar in patients with type 2 diabetes. Another diabetes drug called metformin and Pfizer Inc.'s smoking cessation drug called Chantix were also found to be contaminated with nitrosamines in 2018.

According to the FDA, 37 nanograms of nitrosamine per day is allowed in a drug. Now it is allowing up to 246.7 nanograms because the calculations show the difference in cancer risk is minimal.