Endotoxins are important to Hartley Medical. In addition to impacting the core function of our chosen specialty, intrathecal drug therapy, they also are a singularly fascinating phenomenon. We take them, and Bacterial Endotoxin Testing (BET), very seriously.

Endotoxins are small impurities present in bacteria. They are actually sections of bacterial walls; more specifically, sections of gram-negative bacterial walls. They are also detrimental, even lethal, to the human body. Thus, in the compounding, manufacturing, and administering of parenteral preparations, BET is performed on all commercially-manufactured-parenteral products.

As a college student, I developed a strong interest in parenteral drug therapy and, by association, endotoxin testing. Traditionally, said testing employed 3-5 rabbits as the primary test subjects. The drug was injected into these test rabbits, and the resultant body temperature changes (or lack thereof) were monitored by a well-placed thermometer. If the body temperature varied 0.5 ° or more, the test element was considered pyrogenic, or “fire generating” (causing fever), and indicated the presence of endotoxins.

NOTE: In those early days of endotoxin testing, endotoxins were referred to as pyrogens until it was discovered that not all endotoxins are actually pyrogenic. The distinction was made, and the use of “pyrogen” synonymously with endotoxins was discontinued.

Cued by this revelation and the ongoing evolution of available technology, in 1982 an innovative endotoxin test was developed. I followed its development over the years as I developed my practice, learning more and more about the nature and specifics of this new testing method. In 1998, I contacted Massachusetts’ Associates of Cape Cod. (www.acciusa.com), one of only three companies that manufactured the endotoxin test at the time.

Key to the testing was a lysate, an enzyme, known as Limulus Amebocyte Lysate(LAL). Derived from a HORSESHOE CRAB [Limulus polyphemus] found only on the eastern seaboard of North America along the various coastal bays of Massachusetts and Connecticut, and Japan, the lysate acts to clot and expel bacteria with which the horseshoe crab comes in contact. The crab species has been around for about 250 million years, and for all this time, the lysate has served as the creature’s immune system. Someone researched this phenomenon and found that this lysate has an affinity to the lipopolysaccharide section of bacterial cell walls.

Enthralled by this story and its implications for the field of intrathecal drug therapy, in 1999 I pulled the trigger and bought the equipment that would make it possible for me to conduct my own bacterial endotoxin testing.

This test is very specific and very complicated. We compound our drugs, take samples, and inject the lysate into the test tubes. But, wait, there’s more! You have to perform a standard curve. The rationale for the standard curve was to ensure the lysate reaction worked with a cross section of endotoxin concentrations.  If that standard curve played out correctly — if the mixture clotted — you said “OK, I’m prepared to submit samples of my active drug.”

We test our samples in duplicates. This discipline of not only running a standard curve, but preparing samples in duplicate, both spiked and non-spiked, took us to a new level of “You’ve gotta be kidding! It also took us to a new level of expertise in analytical chemistry. We explored, learned, and grew. In time, we mastered this sometimes maddeningly complicated procedure.

We continue to administer this test on our compounded preparations, with new advanced instruments. It has made all the difference in our finished product.  We learned volumes about our preparations and how they interacted with the enzyme; how they effect the way the enzyme can enhance or inhibit the outcomes. We’ve turned that knowledge and know-how into a significantly serious service and quality assurance asset for our company, our clients, and our shared patients.