Binding and Metabolism of Nitroglycerin by Rat Blood Plasma

The ultrafiltration technique was employed to measure the extent of 14C-nitroglycerin binding by the proteins of rat blood plasma. Over the concentration range of 50-500 μg of nitroglycerin/ml of plasma, approximately 60% of the drug was bound. During the course of the binding experiments, nitroglycerin was metabolized to glyceryl dinitrates. Twice as much glyceryl-1, 3-dinitrate was formed as glyceryl-1, 2-dinitrate, indicating a strongly preferential attack upon the 2-position rather than upon the terminal positions. The metabolites were also bound by plasma proteins with glyceryl-1,2-dinitrate being held more extensively (about 60%) than glyceryl-1,3-dinitrate (35%).