Filtration removal of endotoxin (pyrogens) in solution in different states of aggregation.

Bacterial lipopolysaccharides are recognized as the major cause of pyrogenic reactions from parenteral solutions. Molecular filtration was used to remove these pyrogenic molecules (endotoxins) from contaminated parenteral solutions. Because bacterial lipopolysaccharides can exist in different states of aggregation, depending on the composition of the solution they are suspended in, the full range of possible states of aggregation was examined by using filters with a wide range of pore sizes. Filters of different pore sizes retained endotoxin lipopolysaccharide presumed to be in the vesicle form, the micelle form, or the detergent-solubilized form in aqueous solutions. Endotoxins (pyrogens) were successfully removed from artificially contaminated solutions of concentrated antibiotics by using filters of 10,000-nominal-molecular-weight limit.