Absorption kinetics of a 14C-labelled Escherichia coli extract after oral administration in mice

The fate of orally administered total 14C-labelled Escherichia coli extract (TEC, OM-89) was compared to that of its major 14C-labeled high molecular weight fractions (HEC, > 30 kD) in mice. High molecular weight substances (> 30 kD) were observed in blood 1 h after oral administration of the products, TEC and HEC. This suggests absorption from the digestive tract of the total E. coli extract. Blood clearance after 24 h indicates that the product was rapidly eliminated or taken up by the tissues. Its highest organ distribution among the measured organs was found in the liver, followed by the spleen and the Peyer's patches. Low molecular weight fractions (LEC, < 30 kD) were also used as control. This pilot study provides a rationale for in vivo pharmacological investigations with oral administration of the E. coli immunomodulating extract OM-89.