Clonidine (0.01 to 0.16 mg/kg) and lofexidine (0.01 to 0.64 mg/kg) produced a dose-dependent inhibition of diarrhea induced by castor oil treatment in the rat. Both drugs were more potent and longer acting than diphenoxylate. Pre- and posttreatment with naloxone (5 mg/kg) failed to prevent or antagonize the antidiarrheal effect of clonidine and lofexidine. These data suggest that clonidine and lofexidine may provide potent antidiarrheal activity of a nonnarcotic nature.
