The present invention relates to a new peptide called Antisecretory Factor (AF) 17 which is an isolated recombinant and/or synthetically produced which has a t½ of at least 1.8 h. The peptide is e.g. useful for normalizing pathological fluid transport and/or inflammatory reactions in animals and in humans. AF-17 and pharmaceutical compositions of AF-17 can e.g. be used for treating and/or preventing TBI and/or secondary brain injuries associated with TBI, as well as for treating and/or preventing acquired brain injuries and to optimize cancer treatment.