Endotoxin Testing of Biopharmaceuticals: Comparison of Lal and Recombinant Factor C Assays

Endotoxin control is a release requirement for every parenteral medicine, and the Limulus amebocyte lysate (LAL) test has dominated it for decades. Recombinant factor C (rFC) assays now offer an animal-free alternative. This short review, which reports no new data, compares the two approaches using the published literature. It describes the cascade chemistry behind each reagent, assay formats, interference and low endotoxin recovery, glucan response, reagent supply, and regulatory status, and considers what validation a laboratory needs before changing method. Published comparisons show close agreement for standards and for most products, with advantages for rFC in specificity and sustainability, but independent multi-site studies on complex biologics remain limited.