Pharmacokinetics of nitroglycerin in rats

The plasma nitroglycerin levels obtained after intracardial (0.7 mg/kg), oral (7 mg/kg), and topical (7--14 mg/kg) doses of nitroglycerin in rats are reported. Nitroglycerin followed essentially one-compartment kinetics after intracardial administration, showing a mean half-life of about 4 min and a mean apparent volume of distribution of about 3 liters/kg. After oral drug administration, "flip-flop" kinetics were evident. The mean oral bioavailability was determined to be 1.6%, firmly supporting the contention that nitroglycerin is extensively metabolized during first passage through the liver. Under the experimental conditions studied, no detectable levels of nitroglycerin were observed after topical application.