The effect of adjuvants on the colonie absorption of cefmetazole and [Asu1,7]-eel calcitonin in rats: concentration dependent absorption pathways

Rat colonie absorption of cefmetazole and [Asu1,7]-eel calcitonin was enhanced by coadministration of sodium salicylate, disodium ethylenediaminetetraacetic acid, diethyl ethoxymethylenemalonate or trifluoperazine. Colonie absorption of cefmetazole and eel calcitonin, enhanced by various concentrations of either EDTA or trifluoperazine, appeared to occur via a paracellular pathway. Diethyl maleate did not enhance colonie absorption of eel calcitonin, but it did significantly enhance colonie absorption of cefmetazole, demonstrating the importance of a paracellular absorption pathway for eel calcitonin. Although low concentrations of DEEMM and salicylate enhanced the colonie absorption of only cefmetazole (having a low molecular weight of 471), those adjuvants at high concentrations remarkably enhanced the colonie absorption of both cefmetazole and the macromolecular peptide, eel calcitonin (mol. wt. 3363). This observation suggests two different adjuvant mechanisms, depending on the concentration of the adjuvant.