Nasal absorption of digoxin in rats.

The nasal administration of digoxin was studied in rats and compared to intravenous, intraduodenal and rectal administration of the drug. The results indicated that the plasma level of digoxin after nasal administration was comparable to the level after intravenous injection. Administration by the intraduodenal and rectal routes resulted in considerably lower plasma levels. These data reveal that digoxin absorption across the nasal membranes is a reasonable approach. In the in situ nasal and intestinal perfusion experiments, digoxin disappeared from the perfusate following the apparent first-order kinetics. The nasal and intestinal absorption rate of digoxin was reduced by an increase in the perfusion volume. The plot of absorption rate constant against 1/volume resulted in a straight line, suggesting that digoxin is absorbed from nasal mucosa by a passive diffusion process.