Sterile vs. Pyrogen-free: What’s the difference and why should I care?

Sterile vs. pyrogen-free – it’s important to your work and you need to know the difference. First of all, what is a pyrogen? Simply, a pyrogen is any substance that causes a fever. The most commonly thought of pyrogens are bacterial endotoxins and exotoxins, although the host body (human or animal) can also produce pyrogens.  The most commonly assayed for pyrogen is lipopolysaccharide, or LPS. It is a component of the bacterial wall of Gram-negative bacteria and is released upon breakdown of the cell wall or bacterial cell lysis.

So, if something has been sterilized, it should be pyrogen-free right? Wrong!

WHEATON CryoELITE in BenchMate Rack

Sterility ensures the absence of viable living bacteria. However, the act of sterilizing a contaminated vial can actually result in the release and deposit of pyrogens, as sterilization destroys bacteria, leading to bacterial cell lysis and release of LPS or other endotoxins and exotoxins.

Make sure your products are manufactured in a pyrogen-free setting that prevents the deposition of bacteria and other agents on the products. Required sterile products would then undergo a separate sterilization process dependent on the product and/or end-users’ needs. Thus, specific items may be sterile, sterile and pyrogen-free, or pyrogen-free but not sterile.

Thus, it’s important to consider your specific needs in order to ensure that your needs are met by your product of choice.

Key Points:

1)      Sterile does not mean pyrogen-free.

2)      Manufacturing that takes into account pyrogen-free environments are best.

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