Nitrite and Nitrate Pharmacokinetics in the Dog, Sheep, and Pony

Abstract

SUMMARY Elimination kinetics of nitrite and nitrate in the dog, sheep, and pony were determined. The elimination half-lives of nitrite were 0.499, 0.475, and 0.566 hours in the dog, sheep, and pony, respectively; those of nitrate were 44.681, 4.233, and 4.821 hours. Apparent specific volumes of distribution (V′d) of nitrite were variable among the 3 species—1,623.7 ml/kg in the dog, 278.0 ml/kg in the sheep, and 191.6 ml/kg in the pony. The V′d of nitrate were less varied—dog, 238.5 ml/kg; sheep, 291.1 ml/kg; and pony, 209.3 ml/kg. In the in vitro studies on protein binding in canine plasma, the extent of nitrite-protein binding varied directly with concentrations of 5 to 25 μ g of NO 2 -/ml (4.5 to 13.6% bound), but inversely with concentrations of 50 to 100 μ g of NO 2 -/ml (9.8 to 8.8% bound). Less than 1% of nitrate was bound to canine plasma at equimolar concentrations (5 to 100 μ g of NO 3 -/ml).