Editorial: Quality Assurance in Compounding, Part XI

United States Pharmacopeia (USP) Chapter <85> Bacterial Endotoxins Test

What is the difference between pyrogen-free and endotoxin allowable limits? The earlier designation of "pyrogen-free" was based on the rabbit pyrogen test where a group of rabbits were injected with the product and were monitored for an increase in body temperature. This was a somewhat crude test and if there was no increase in temperature or an increase of less than 0.5�C, the product was designated as "pyrogen free" (See USP Chapter <151> Pyrogen Test). However, the pyrogen-free concept is confusing to some and the phrase endotoxin-free is used erroneously. It is extremely difficult to make something endotoxin-free.

The bacterial endotoxins test is much more sensitive and easier to perform than the pyrogen test and is the one most commonly used today. Being more sensitive, very low levels of endotoxins can be detected. Endotoxins are a part of the lipopolysaccharide complex that forms the outer envelope of gram-negative bacteria, and are released during the lysis of a microorganism or during cell division. The bacterial endotoxins test (BET) is a very sensitive test based upon clot-formation of the enzyme Limulus Amebocyte Lysate (LAL) in the presence of endotoxins.

Kits are available for doing the endotoxin LAL test "in-house" or it can be out-sourced. There are three primary types of LAL endotoxin testing methods; (1) the gel-clot method, (2) the chromogenic method, and (3) the turbidimetric method. All three methods can be used provided there are no interferences that can inhibit the reaction. Each method has its advantages and disadvantages; the gel-clot method is probably the most widely used and is believed to be the most accurate.

Since this test gives an endotoxin "level", a cutoff level must be established for each and every compounded preparation. This was previously discussed in detail, and a table of maximum endotoxin unit levels has been previously published,¹ and this information is available online in the CompoundingToday.com Endoxin Limits database. A standard operating procedure has been provided for this.² After the test results are obtained, they can be compared to the calculated endotoxin load for a pass/fail determination.

A laboratory that does this test will need to know the exact composition of the compounded formula and the intended dose for the patient per day (per hour) to determine whether or not the compounded preparation contains excessive endotoxins. All the ingredients can contribute to the endotoxin load, including sterile water for injection. The Endotoxin Load (EL) the body can generally tolerate without experiencing the associated adverse effects is 5.0 endotoxin units/kg (EU/kg) per hour for parenterals (except for intrathecal) and 0.2 EU/kg per hour for the intrathecal route of administration. The equation used for the generally accepted endotoxin limit (EL) is defined as: EL = K/M; where K is the threshold human pyrogenic dose of endotoxin per kg of body weight per hour, and M is the maximum recommended human dose/kg of body weight that would be administered in a single one-hour period.

If a pharmacy does their own in-house testing, it is recommended to periodically send a duplicate sample to a qualified laboratory and compare the results.


Loyd V. Allen, Jr., PhD, RPh
Editor-in-Chief

1. Allen LV Jr. Quality-control analytical methods: Allowable endotoxin levels in sterile preparations. IJPC 2004; 8(6): 479-485.
2. Allen LV Jr. Standard operating procedure: Calculating the endotoxin load in compounded sterile preparations. IJPC 2004; 8(6): 466-467.

How much do you know about how a particle counter works? We talk about particulates in solutions and ISO Class 5, working environments, etc. but what does that really mean? Here is a good article about particle counters: http://cr.pennnet.com/display_article/293103/15/ARTCL/none/none/Understanding-particle-counting-technology/?pc=ENL

The following story, just recently published, supports the different routes of administration using compounded BHRT.

Systemic lupus erythematosus and hormone replacement therapy.
Gompel A, Piette JC. Menopause Int 2007; 13(2): 65-70.

ABSTRACT
The indications for hormone replacement therapy (HRT) in postmenopausal women are the treatment of climacteric symptoms and the prevention of osteoporosis. Women with systemic lupus erythematosus (SLE) are more likely to have a premature menopause, osteoporosis and cardiovascular disease. HRT can induce SLE flares and cardiovascular or venous thromboembolic events. Therefore it should not be used in women with active disease or those with antiphospholipid (aPL) antibodies. In general, it should be used only for patients without active disease, a history of thrombosis or aPL antibodies. Non-oral administration of estrogen is recommended because of its lesser effect on coagulation. With regard to the progestogen, progesterone or pregnane derivatives are preferred. Otherwise, non-estrogen-based strategies should be used.

Stuffy store?
Consider the use of fans, especially during the summer. Ceiling fans are especially effective and, in addition to moving the air, also add character to the appearance of the store. Ceiling fans come in many decorative varieties and they tend to last for many, many years. Also, they are generally quite economical to use and oftentimes, the store temperature can be set a degree or so warmer so they might actually save you money.