European Pharmacopoeia paved the way for rFC adoption: Integration of Recombinant Factor C (rFC) into Chapter 2.6.14

The European Pharmacopoeia (Ph. Eur.) is undergoing a transformative update to its Bacterial Endotoxin Testing (BET) standards, signaling a new era in pharmaceutical quality control. With the introduction of Method G: Fluorimetric end-point method using recombinant Factor C (rFC) into Chapter 2.6.14, “Bacterial Endotoxins,” the Ph. Eur. is paving the way for definitive compendial adoption of a modern, sustainable substitute for the traditional Limulus amoebocyte lysate (LAL) assay.

This project is more than a technical revision—it represents a paradigm shift in how the pharmaceutical industry approaches endotoxin detection, aligning regulatory frameworks with scientific innovation and sustainability goals and puts rFC on equal footing as all existing LAL tests.

For decades, the LAL assay has been the gold standard for detecting bacterial endotoxins in pharmaceutical products. Derived from the blood of the horseshoe crab (Limulus polyphemus), LAL has been instrumental in ensuring the safety of injectable drugs, vaccines, and medical devices. However, the reliance on a vulnerable marine species has raised ethical, ecological, and supply chain concerns.

Recombinant Factor C (rFC) offers a compelling solution. Produced through recombinant DNA technology, rFC mimics the endotoxin-sensitive component of the horseshoe crab’s immune response without involving any animal-derived materials. Its advantages include:

• High specificity and sensitivity to endotoxins
• Reduced batch-to-batch variability compared to LAL
• No limulus use, supporting the 3Rs (Replacement, Reduction, and Refinement) in scientific testing
• Sustainable and scalable production
• Allows for development of derivate assays (including ENDOLISA®, with endotoxin bound by a phage protein for difficult to test products) and ENDOZYME® II GO pre-spiked plates and strips 

To further support the adoption of rFC, the European Pharmacopoeia is proposing the integration of Chapter 2.6.32—which currently provides guidance on rFC testing—directly into Chapter 2.6.14. This consolidation is designed to:

• Unify regulatory guidance under a single, comprehensive chapter
• Eliminate fragmentation and reduce ambiguity for users
• Establish rFC as an equal alternative to LAL in all relevant monographs
• Facilitate broader implementation across the pharmaceutical industry

This move could not only simplify compliance but also reinforce the legitimacy and reliability of rFC as a validated method for endotoxin detection.

The integration of rFC into the core of the Ph. Eur. reflects a broader trend in regulatory science: the shift toward innovative, ethical, and sustainable testing methods. For pharmaceutical manufacturers, this update offers:

• Greater flexibility in choosing validated endotoxin testing methods
• Streamlined regulatory submissions for products using rFC
• Alignment with global pharmacopoeial trends, including those in the United States and Japan, which have also recognized rFC

Moreover, this change could support the pharmaceutical sector’s commitment to environmental stewardship  and animal welfare, without compromising on safety or efficacy.

As the European Pharmacopoeia continues to evolve, the project of rFC integration into Chapter 2.6.14 marks a significant milestone in the modernization of quality control practices. It reflects a forward-thinking approach that balances scientific rigor with ethical responsibility. 

Pharmaceutical companies, regulators, and stakeholders are encouraged to stay informed about the implementation timeline and prepare for the transition. Embracing rFC not only meets regulatory expectations but also contributes to a more sustainable and humane future for pharmaceutical testing.