FDA balks at recalls for 2 tuberculosis meds despite possible carcinogen contamination

FDA Building
The FDA has searched high and low for drugs contaminated with compounds from the potentially cancer-causing nitrosamine family. (FDA)

After facing global recalls tied to a family of probable carcinogens, the FDA has been on the hunt for other meds with the same cancer-causing contaminants. The agency hit the bullseye with two generic tuberculosis meds, but shortage fears will keep both on U.S. shelves for now. 

Despite finding elevated levels of possible carcinogens in tuberculosis meds rifampin and rifapentine, the FDA will not request a withdrawal from U.S. shelves over fears a recall would cause a supply shortage, the agency said Wednesday.

The FDA will allow manufacturers to "temporarily distribute" the meds to U.S. consumers as they work to lower reported levels of 1-methyl-4-nitrosopiperazine (MNP) and 1-cyclopentyl-4-nitrosopiperazine (CPNP), two compounds in the nitrosamine family. 

Nitrosamines—most notably N-nitrosodimethylamine (NDMA)—have been identified as probable human carcinogens and linked to recalls of the generic diabetes med metformin, generic and branded heartburn drug Zantac, and the "sartan"-based family of blood pressure medications. 

The FDA said it's investigating the origin of the contamination for both tuberculosis medicines and is "developing testing methods" to better identify MNP and CPNP in tested lots. 

RELATED: Metformin recalls continue as Bayshore pulls diabetes drug on carcinogen scare

Bayshore is the most recent drugmaker to pull its version of metformin off shelves after FDA investigators identified high levels of NDMA. The FDA began requesting voluntary recalls of certain metformin products in May after internal testing contradicted the agency's earlier findings of normal NDMA levels in tested samples.