RT Journal Article
SR Electronic
T1 ABSORPTION OF CARDIAC GLYCOSIDES FROM THE RAT RESPIRATORY TRACT
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 105
OP 111
VO 187
IS 1
A1 Lanman, Robert C.
A1 Gillilan, Roberta M.
A1 Schanker, Lewis S.
YR 1973
UL http://jpet.aspetjournals.org/content/187/1/105.abstract
AB The absorption of tritium-labeled cardiac glycosides from the respiratory tract of anesthetized rats was studied after intratracheal administration of 0.1 ml of Krebs-Ringer-phosphate solution (pH 7.4) containing a glycoside. At various times after administration, the lungs and trachea were removed and assayed radiochemically for unabsorbed drug. The half-times for absorption, in minutes, were as follows: digitoxin, 0.3; digoxin, 1.0; ouabain, 67; and dihydroouabain, 87. Absorption rates, expressed as firstorder rate constants, ranked in the same order as the chloroform/water (pH 7.4) partition coefficients of the compounds which were as follows: digitoxin, 123; digoxin, 17; ouabain, 0.004; and dihydroouabain, 0.0008. Thin-layer chromatographic analysis of lung extracts demonstrated that unabsorbed drug was unaltered metabolically. When the initial concentration of the glycosides was varied over a 100-fold range, the absorption rates were directly proportional to concentration. The results suggest that these giycosides are absorbed mainly by passive diffusion across a lipoid-pore membrane and that the pore route is most important for glycosides of lowest lipid solubility. © 1973 by The Williams & Wilkins Company