Purpose. To determine the human jejunal permeability of cimetidine and ranitidine using a regional jejunal perfusion approach, and to integrate such determinations with previous efforts to establish a baseline correlation between permeability and fraction dose absorbed in humans for soluble drugs. Methods. A sterile multi-channel perfusion tube, Loc-I-Gut®, was inserted orally and positioned in the proximal region of the jejunum. A solution containing cimetidine or ranitidine and phenylalanine, propranolol, PEG 400, and PEG 4000 was perfused through a 10 cm jejunal segment in 6 and 8 subjects, respectively. Results. The mean Peff (± se) of cimetidine and ranitidine averaged over both phases were 0.30 (0.045) and 0.27 (0.062) × 10-4 cm/s, respectively, and the differences between the two were found to be statistically insignificant. The mean permeabilities for propranolol, phenylalanine, and PEG 400 averaged over both phases and studies were 3.88 (0.72), 3.36 (0.50), and 0.56 (0.08) × 10-4 cm/s, respectively. The differences in permeability for a given marker were not significant between phases or between the two studies. Conclusions. The 10-fold lower permeabilities found for cimetidine and ranitidine in this study, compared to propranolol and phenylalanine, appear to be consistent with their less than complete absorption in humans.
Bibliographical noteFunding Information:
This work was supported in part by FDA, Grant FD014, and the General Clinical Research Center (GCRC) of the University of Michigan, NIH M01RR00042. Ok-Nam Kim was supported in part by a grant from the Korean Government and Nasir M. Idiadek was supported in part by a grant from Jordan University of Science and Technology. The valuable assistance of John Wlodyga and the staff of the GCRC are gratefully acknowledged.
- Biopharmaceutic classification system
- Drug absorption
- Intestinal permeability