Distribution of cephalothin to the exudate in comparison with the plasma or lymph concentrations in croton oil-induced inflammatory rats.

The transport of cephalothin (CET) to the exudate was investigated in croton oil-induced inflammatory rats following the intramuscular administration of CET-aqueous solution, CEt-O/W emulsion, or CET-W/O emulsion. The lymphatic transport of CET was the highest following the administration of W/O emulsion. The exudate level of CET was in a decreasing order of W/O emulsion, O/W emulsion, and aqueous solution. In the rat whose blood vessels at femoral rectus, the site of administration, were ligated, the plasma level was decreased by the administration of aqueous solution, but not by W/O emulsion. The exudate level of CET was significantly higher in case of W/O emulsion. Possible mechanisms involved are discussed.