Application of Recombinant Factor C Reagent for the Detection of Bacterial Endotoxins in Pharmaceutical Products

PDA J Pharm Sci Technol. 2017 Sep-Oct;71(5):405-412. doi: 10.5731/pdajpst.2017.007849. Epub 2017 Jul 20.


Recombinant Factor C (rFC) is non-animal-derived reagent used to detect bacterial endotoxins in pharmaceutical products. Despite the fact that the reagent was first commercially available nearly 15 years ago, the broad use of rFC in pharmaceutical industry has long been lagging, presumably due to historical single-source supplier concerns and the lack of inclusion in worldwide pharmacopeias. Commercial rFC reagents are now available from multiple manufacturers, thus single sourcing is no longer an issue. We report here the successful validation of several pharmaceutical products by an end-point florescence-based endotoxin method using the rFC reagent. The method is equivalent or superior to the compendia bacterial endotoxins test method. Based on the comparability data and extenuating circumstances, the incorporation of the end point fluorescence technique and rFC reagent in global compendia bacterial endotoxins test chapters is desired and warranted.LAY ABSTRACT: Public health has been protected for over 30 years with the use of a purified blood product of the horseshoe crab, limulus amebocyte lysate. More recently, this blood product can be produced in biotech manufacturing processes, which reduces potential impacts to the horseshoe crab and related species dependent upon the crab, for example, migrating shorebirds. The pharmaceutical industry has been slow to adopt the use of this reagent, Recombinant Factor C (rFC), for various reasons. We evaluated the use of rFC across many pharmaceutical products, and in other feasibility demonstration experiments, and found rFC to be a suitable alternative to the animal-derived limulus amebocyte lysate. Incorporation of rFC and its analytical method into national testing standards would provide an equivalent or better test while continuing to maintain patient safety for those who depend on medicines and while securing pharmaceutical supply chains. In addition, widespread use of this method would benefit existing animal conservation efforts.

Keywords: Bacterial endotoxins; End point fluorescence; Limulus amebocyte lysate (LAL); Recombinant Factor C (rFC).

MeSH terms

  • Animal Use Alternatives
  • Animals
  • Arthropod Proteins*
  • Drug Industry / methods
  • Endotoxins / analysis*
  • Enzyme Precursors*
  • Humans
  • Indicators and Reagents*
  • Limulus Test / methods
  • Pharmaceutical Preparations / analysis*
  • Pharmaceutical Preparations / standards
  • Recombinant Proteins
  • Serine Endopeptidases*


  • Arthropod Proteins
  • Endotoxins
  • Enzyme Precursors
  • Indicators and Reagents
  • Pharmaceutical Preparations
  • Recombinant Proteins
  • Serine Endopeptidases
  • Limulus clotting factor C