Rioprostil Prevents Aspirin-Induced Fecal Blood Loss in Dogs

Abstract

Rioprostil, a primary alcohol prostaglandin E₁ analog, prevents gastric lesion formation induced by a variety of irritants, including aspirin, in rats and dogs. In the present study, rioprostil reduced both gastric lesion formation and fecal blood loss in dogs caused by daily aspirin administration (1,950 mg/day) for 3 consecutive days. A gastric antisecretory dose of 100 μg/kg p.o. t.i.d. of rioprostil reduced fecal blood loss by 96% to a level (0.76 ± 0.10 mg Hb/g stool) similar to basal blood loss in non-aspirin-treated vehicle dogs (0.61 ± 0.08 mg Hb/g stool) as determined by HemoQuant® assay. A nonantisecretory dose of rioprostil (1 μg/kg p.o. t.i.d.) reduced fecal blood loss by 70% compared to vehicle-treated dogs. Gastric lesion severity scores in dogs treated with 100 or 1 μg/kg p.o. t.i.d. of rioprostil were 61 and 52% lower, respectively, than the mean severity score in the vehicle-treated group. There was a highly significant (p < 0.001) correlation between gastric lesion score and fecal blood loss independent of the treatment each dog received. The efficacy of a nonantisecretory dose suggests that the gastric lesion effect of rioprostil may be independent of gastric antisecretory effects. The correlation of fecal blood loss with gastric lesion score suggests the possibility that either measurement may be used as an indication of gastric lesion occurrence or severity.