It is intended to provide an agent for accelerating mucosal absorption enablingoral, transnasal or transpulmonary administration of a peptide drug which showsvery poor mucosal absorption and therefore is administered only through injection,and to improve mucosal absorption of a peptide drug through the intestine, lungand nose by allowing the peptide drug to act together with a substance having aC-terminal fragment (C-CPE)of enterotoxin (CPE) produced by Clostridium perfringenswhich is a bacterium of the genus Clostridium, more specifically, an amino acidsequence formula of C-CPE or a mutant with substitution and/or deletion of oneor several amino acid residues of C-CPE. A composition for mucosal administrationof the invention has been observed to have a significant effect of acceleratingabsorption of a peptide drug such as human parathyroid hormone hPTH(1-34), humanmotilin or human ghrelin in the mucosa of the intestine, lung, nose or the like,and does not have tissue toxicity unlike conventional substances for acceleratingmucosal absorption and is excellent in safety.
