Effect of somatostatin analog (SMS 201-995) on in vivo intestinal fluid transport in rats. A limited systemic effect.

Somatostatin analog, SMS 201-995, effectively inhibits the release of hormones from gastrointestinal endocrine tumors and reduces hormonally mediated diarrheas. Its clinical efficacy in nonhormonally mediated diarrhea is limited, despite a potent antisecretory and proabsorptive effect in vitro. The effect of serosal addition of SMS 201-995 on in vitro short-circuit current responses in rat intestine is dependent upon chloride and more marked in colon and ileum than jejunum. In contrast, in vivo loop studies demonstrated that systemic administration of SMS 201-995 for five consecutive days produced a paradoxical decrease in basal colonic fluid absorption with no effect in jejunum or ileum. Furthermore, systemically administered SMS 201-995 did not alter cholera toxin-stimulated intestinal secretion. We conclude that despite a previously identified intestinal antisecretory and proabsorptive effect of SMS 201-995 in vitro, this effect is not seen in vivo and may explain the limited use of SMS 201-995 as an antidiarrhoeal agent in nonhormonally mediated diarrhoea.