ABSTRACT
Experimentally the metabolic stability of GHRP-6 (SK&F 110679) or of hexarelin has been confirmed at least in the rat from which more than 50% of these peptides can be recovered unchanged in the bile following their subcutaneous (sc) administration. This observation prompted the SK&F group to observe that GHRP-6 "was not designed with metabolic stability in mind [but] it is tempting to speculate that the structural features that are important for receptor binding and pharmacological activity of these peptides may also confer metabolic stability, protecting them from degradation by peptidases" (6). We propose the term impervious peptides to describe the metabolic stability characteristic of this series of secretagogues.
