Endotoxins, also called LPS, are the component of the outer membrane of gram-negative bacteria and are released into the circulation upon disruption of the intact bacteria (death, cell lysis). Endotoxin is commonly found everywhere in our environment, and it is the most significant pyrogen in parenteral drugs and medical devices.

Endotoxins are also present in the digestive system. Their presence in the blood stream may cause septic reactions with a variety of symptoms such as fever, hypotension, nausea, shivering and shock. High concentrations can lead to serious complications such as disseminated intravascular coagulation (DIC), endotoxin shock and adult respiratory distress syndrome (ARDS). Endotoxins are known to activate complement, the kinin system, leukocytes, platelets and endothelial cells and are the “enemy” of both in vitro and in vivo study of blood–material interactions. In vivo, they may lead to the complications mentioned above, while in vitro, the presence of this contaminant may affect the results and compromise the conclusions.