ENKEPHALINS AND ENKEPHALINASE INHIBITORS IN INTESTINAL FLUID AND ELECTROLYTE TRANSPORT

Opioids have long been known to inhibit intestinal fluid and electroly te secretion. They act locally on central and peripheral opiate recept ors where they are rapidly degraded by neuropeptidases, the major one being enkephalinase (EC 3.4.24.11). A number of studies have shown tha t, when the problem of degradation can be overcome, enkephalins have p otent antisecretory properties. In 1980, an enkephalinase inhibitor wa s described which increased the functional availability of enkephalins . More recently an orally active enkephalinase inhibitor, acetorphan, has been shown to inhibit infectious and chemically induced diarrhoea. Acetorphan does not appear to affect gastrointestinal motility and, a lthough it also inhibits the breakdown of a range of other neuropeptid es, such as substance P and neuropeptide Y, it is a promising agent wi th therapeutic potential.