The Food and Drug Administration is warning consumers and healthcare professionals that certain test strips used to monitor warfarin levels may provide inaccurate International Normalized Ratio (INR) results that could potentially lead to incorrect dosage adjustments.

In November 2018, Roche Diagnostics issued a recall of more than 1.1 million packages of CoaguChek XS PT Test Strips. 

Subsequently, medical product distributor, Terrific Care/Medex Supply LLC issued a voluntary recall of the same test strips; however, these strips were not included in the first recall, as they were not labeled or authorized for sale in the US. Terrific Care/Medex Supply had purchased these test strips (which were distributed by Roche Diagnostics outside the country) from an unknown source, imported and sold them in the US. 

The recall of these test strips has been classified as Class I, the most serious of recalls.

“Using faulty strips can lead to errors in medication dosage that could cause serious harm or death in some patients. That’s why it’s so concerning that this distributor continued to sell these test strips in the US even though domestic sales had been stopped due to safety concerns,” said FDA Commissioner Scott Gottlieb, MD. 

“To reduce risks to patients, we’re warning healthcare providers and the public about the dangers associated with this product.”

The recalled test strips are used with the CoaguChek XS plus, CoaguChek XS Pro, CoaguChek XS professional, CoaguChek XS PST, and CoaguChek Vantus test meter devices. 

The FDA is urging patients and providers to immediately stop the use of test strips purchased from Terrific Care/Medex Supply and use alternative methods (lab test, alternative meter device) to monitor warfarin levels.

“Our top priority is the immediate safety of patients, and we’re taking steps to ensure the products that this company distributed are removed from the market,” added Dr Gottlieb. 

For more information visit FDA.gov.

This article originally appeared on MPR