Depyrogenation: Don’t Give Me Fever

Endotoxins are toxins that are part of the outer membrane of gram-negative bacteria. If endotoxins enter the body, they can cause an immune response that results in symptoms such as fever, shock, and even death in severe cases.

Endotoxins happen to be particularly tricky to remove from glass surfaces, as they can adhere to the hydrophilic (water-loving) molecules of the glass surface.

Because of this property, neither washing nor standard sterilization techniques effectively eliminate the toxins. The endotoxins also have a high heat tolerance, which makes them difficult, but not impossible, to inactivate. More on that on page 2!

Depyrogenation is a process that uses high temperature dry heat to remove pyrogens from a material. In the pharmaceutical industry, pyrogens are of extra concern for injectable products, as injecting these into your bloodstream could cause an adverse reaction.

For this reason, depyrogenation tunnels are utilized to ensure contamination free syringes and vials for injectable products prior to filling. The image below breaks down the various stages of depyrogenation the materials undergo as they move through the tunnel on a conveyor.

Notice the arrows in the diagram. These represent the air flow in the tunnel. All airflow into the chamber is HEPA filtered and flows over the vials to heat them, then down through the base of the tunnel. This ensures only clean air touches the materials as they are depyrogenated.