FDA has warned clinical laboratory staff and healthcare providers against using certain transport media with Hologic’s coronavirus test after receiving reports of cyanide-generating chemical interactions.
The safety notice, which FDA issued Thursday, reiterates warnings in earlier documents from Hologic and the Centers for Disease Control and Prevention. Despite the warnings, some laboratories have used PrimeStore Molecular Transport Medium with Hologic's Panther and Panther Fusion systems.
"The need to avoid guanidine compounds with the Panther and Panther Fusion instruments is included as a prominent warning in the FDA approved instrument operator manual," Hologic said in a statement, noting package inserts were updated in April to remind customers of the risks.
Many molecular laboratory testing protocols use ethanol to decontaminate and clean equipment. Bleach is involved in the handling of Hologic’s assays. The choice between ethanol and bleach has potentially fatal consequences.
Bleach reacts with guanidine-containing materials to produce cyanide gas, rendering it unsafe to use PrimeStore with Hologic’s assays.
Longhorn Vaccines and Diagnostics’ PrimeStore is a transport medium designed to inactivate viruses and stabilize genetic material to prepare samples for shipping at ambient temperatures. To achieve those outcomes, the medium uses guanidine thiocyanate. Like other guanidine-containing materials, the denaturing agent reacts with bleach to generate harmful cyanide gas.
While LabCorp and Quest Diagnostics do not accept PrimeStore, the CDC says the medium can be safely used with the vast majority of coronavirus tests, including those sold by Abbott, Roche and Thermo Fisher. However, as Hologic and CDC have previously stated, the medium cannot be used with Panther systems.
Nonetheless, some laboratories have combined the two products, causing release of hazardous gases. None of the incidents reported to FDA involved injuries to people, but the agency and other parties want to avoid further use of PrimeStore with Hologic assays.
Days before the agency raised the issue, Longhorn sent out an urgent medical device correction. In the notice, Longhorn said it will now ship PrimeStore tubes individually labeled with warnings about the presence of guanidine thiocyanate. Labs that receive unlabeled tubes should contact Longhorn, which has promised to supply labels within two business days. Longhorn is advising labs that are unable to clearly identify the brand of tube to only use those products in systems other than Hologic’s Panther.
CDC has also issued an alert about the need to take precautions when working with PrimeStore medium. The agency said state health departments have shipped PrimeStore packs that are only labeled at the bulk box level.
The alerts issued to date focus on PrimeStore, but FDA said guanidine-containing materials may be found in other transport media. In light of that risk, the agency wants lab staff to assume tubes contain such materials unless they know otherwise. The advice could lead labs to use testing platforms other than Hologic’s Panther systems to process samples taken from potential COVID-19 patients.
More than 1,800 Panther diagnostic platforms have been installed in clinical diagnostic labs globally, including about 200 high-throughput Panther Fusion systems, according to the company.