Comparison of water influx and sieving coefficient in rat jejunal, rectal and nasal absorptions of antipyrine.

Abstract

Permeability characteristics in rat jejunal, rectal and nasal absorption of antipyrine (AP) are discussed in terms of water influx and sieving coefficients. The sieving coefficient in nasal absorption was less than half of those in jejunal and rectal absorptions, which were not significantly different from each other. Apparent water influx in the jejunum was twice that in the rectum, and that in the nose was approximately three times larger than that in the jejunum. The pore size of the water channels in each site was calculated from the sieving coefficient and molecular radius of AP by using the modified Levitt equation. It was concluded that : (1) the nasal membrane is composed of smaller-sized pores but is richer in water channel distribution than the jejunal membrane ; (2) the rectal membrane has similar-sized pores to the jejunal membrane but the water channel distribution is poorer.