A pyrogen is a protein that can induce a fever in a patient by triggering a series of immune reactions. Some are endogenous, developing within the body, and others are exogenous and can be introduced through contaminated food or medication. Exposure to pyrogens can cause severe fever and endanger the patient if the temperature is consistently high or accompanied by complications such as bleeding. A number of steps must be taken to produce products without such compounds and to test finished products for contaminants that may pose a health risk.
In the body, a pyrogen acts as a cytokine, a signal in the immune system. This prompts the immune system to react, causing a spike in temperature. If the fever gets high enough, the patient may develop an altered level of consciousness and fall into a coma. Severe fevers can cause permanent neurological damage along with other health problems and can be fatal in some cases. If a patient was already ill prior to pyrogen exposure, it may degrade the patient's prognosis or their long-term prognosis.
One potential source of these compounds is contaminated medications. Many bacteria produce pyrogens, usually as part of their cell walls. If they get into batches of drugs, they can cause illness in patients. Especially when a drug is injected directly, the patient's body can be hit by an explosion of pyrogens, and the patient can experience a severe injection reaction, sometimes within minutes.
Even sterile solutions can become contaminated if not handled properly during production. Rigorous filtration is necessary at each step to keep the contents pure, and they must be handled with care until sealed in shipping packaging. Pharmaceutical companies use periodic pyrogen testing to verify the safety of their products. If a lot contains pyrogens, the company may destroy or recall it, depending on whether the drug has reached the market.
Direct infections can also cause the release of pyrogens in the body. Some bacterial infections are associated with fevers and other extreme reactions caused by bacterial toxins. Bacteria can produce toxins as a byproduct of other activities or when they die. Paradoxically, antibiotic therapy can sometimes make a patient temporarily sick by killing bacteria and causing a massive release of toxins. If an infection involves bacteria that are known to cause this, the doctor may be careful when prescribing, to limit the risks to the patient.