Endotoxin testing of proteins for parenteral administration using the MonoMac 6 assay

Background: pharmaceutical products containing proteins cause problems in t esting for endotoxin and pyrogens. Many proteins interfere with the LAL tes t and the proteins are immunogenic in rabbits. The monocytic cell line Mono Mac 6 is an alternative assay for detection of endotoxin and other pyrogen s. Objective: To evaluate the use of the Mono Mac 6 assay for quantitative det ection of endotoxin in proteins. Method: The quantitative detection of endotoxin in the three pharmaceutical products human albumin, gamma-globulin and somatropin was evaluated. Results: For the three proteins the detection limit of the Mono Mac 6 assay was far below the threshold endotoxin limit described by the European Phar macopoeia. Interference of two of the proteins with the Mono Mac 6 assay wa s observed, but the problems could be overcome either by dilution of the pr oduct or by comparison of the test with an endotoxin standard curve prepare d in a solution of the respective pyrogen-free protein. Conclusion: The Mono Mac 6 assay is a reliable method for quantitative dete ction of endotoxin in proteins.