While endotoxin and pyrogen testing might not be the sexiest of topics, they are extremely important topics for creating a safe sterile product. I believe that FDA has made your job easier by their recent publication of the guidance titled Pyrogen and Endotoxins Testing ‒ Questions and Answers (Edition 2) yesterday (here). It contains a list of 13 questions with answers that address recommendations for “biological product, drug, and device firms on FDA’s current thinking concerning the testing recommendations and acceptance criteria in the United States Pharmacopeia (USP) Chapter <85> “Bacterial Endotoxins Test”, USP Chapter <161> “Medical Devices ‒ Bacterial Endotoxin and Pyrogen Tests”, and the Association for the Advancement of Medical Instrumentation (AAMI) ST72:2002/R2010, Bacterial Endotoxins ‒ Test Methodologies, Routine Monitoring, and Alternatives to Batch Testing (AAMI ST72).”

FDA notes that both the published USP compendial and AAMI documents provide appropriate information for testing and limits for endotoxin and pyrogens; however, the Agency has provided this guidance to provide its current thinking on the regulatory perspectives to aid firms regarding the submission and maintenance of pyrogen and endotoxins testing for FDA regulated products. FDA also notes that it has withdrawn its “Guideline on Validation of the Limulus Amebocyte Lysate Test as an End-Product Endotoxin Test for Human and Animal Parenteral Drugs, Biological Products, and Medical Devices, was published in 1987 (the 1987 Guidance) and Version 1 of this Guidance was published in 2012.”

Here are the 13 questions:

  • How do I establish sampling for in-process testing and finished product release?
  • When is retesting appropriate?
  • Is sample storage and handling important?
  • Can finished product samples for analysis of bacterial endotoxins be pooled into a composite sample prior to analysis?
  • May a firm use alternative assays to those in the USP for a compendial article?
  • What is the best process for transitioning from one alternate bacterial endotoxins test (BET) method to another?
  • What happened to the endotoxins limit table in Appendix E of the 1987 Guidance?
  • How can Quality by Design concepts support endotoxins limits?
  • When is the USP Chapter <151> “Pyrogen Test” (the rabbit pyrogen test) appropriate?
  • How would an appropriate endotoxin limit be determined for a veterinary product that targets multiple species?
  • What are the endotoxins limits for medical devices?
  • What is the FDA’s expectation for regular screening of therapeutic drug products?
  • Are control standard endotoxins still acceptable for use in running bacterial endotoxins tests?

As you read through the guidance document, you will get a flavor of the Agency’s current thinking regarding the use of alternate methods, a continued emphasis on the reduction of animal testing (e.g., the rabbit pyrogen test) when appropriate, and the need to confirm the use of alternate methods the way that one might with any preferred non-compendial method by demonstrating equivalence of the alternate method to that of the compendial method. It further provides endotoxin limits for medical devices and provides examples of cumulative endotoxin limits for the use of multiple units of a specific device or multiple different devices that may be used in a single procedure among other topics.

The guidance will likely resolve a lot of previously unanswered questions that firms found out about only when receiving deficiencies in their application reviews. Paying close attention to the guidance will likely ease your burden regarding supply of appropriate endotoxin and pyrogen information in your submissions.