process obeyed apparent first-order kinetics. The results obtained from three animals are shown in Table I.
Preliminary experimentation indicated that halflives obtained from different jejunal segments in the same dog did not vary from one another by more than 15%. These results are thus suggestive of a meaningful relationship between intestinal blood perfusion and drug absorption rate. In most instances, a 4 0 4 0 % reduction in mesenteric blood flow resulted in a dramatic increase in the absorption half-life for sulfaethidole.
Mesenteric circulation is subject to alteration from a wide variety of sources, and some of these will be examined and discussed in a future publication. However, it is obvious that adequate precautions should be taken to assure that significant differences in intestinal blood perfusion rates do not exist among the different animals used in a particular absorption study. Unless such precautions are taken, comparisons of the drug absorption data obtained from the various animals should be viewed with a degree of caution.
Although the data reported herein do confirm that the intestinal drug absorption process is hindered by a decrease in vascular perfusion, additional studies must be designed to quantitate the effects of fasting on intestinal blood flow before ascribing a causative role to this factor in our previous experiments.