AJP - Cell Physiology, Vol 234, Issue 5 191-C197, Copyright © 1978 by American Physiological Society
Pulmonary absorption of drugs in the neonatal rat
J. A. Hemberger and L. S. Schanker
To compare the pulmonary absorption of drugs in newborn rats (3-27 days
old) with that in adults, 0.01-0.1 ml of Krebs-Ringer phosphate solution
(pH 7.4) containing a drug was administered to anesthetized animals by way
of a catheter introduced through a tight-fitting tracheal cannula. After
various times, lungs and trachea were removed and assayed for drug that
remained. Semilogarithmic plots of percent drug remaining against time
yielded a straight line for each compound. The lipid-soluble drugs procaine
amide and sulfisoxazole were absorbed at similar rates in newborn and adult
rats. In contrast, the lipid-insoluble drugs tetraethylammonium,
p-aminohippuric acid, and mannitol were absorbed approximately 2 times more
rapidly in younger rats (3-12 days) than in older animals (18 day, 27 day,
or adult). The results suggested that the respiratory tract membranes of 3-
to 12-day-old rats have a greater porosity than those of older animals.
