Nitroglycerin-induced heparin resistance: absence of interaction at clinically relevant doses

A diminution in the anticoagulant effect of IV heparin with concomitant use of IV nitroglycerin has been reported. However, recent reports have disputed the existence of this interaction. The objective of this study was to assess the potential interaction of these agents in a clinical setting. Forty-five patients hospitalized with angina or acute myocardial infarction received low-dose nitroglycerin (5-20 micrograms/minute), and 13 received high-dose nitroglycerin (80-240 micrograms/minute). The two groups were similar with respect to sex, age, weight, and angina class; however, the high-dose group had a greater degree of congestive heart failure. The heparin dose required to achieve therapeutic anticoagulation did not differ between the groups. Results suggest no inhibition of heparin anticoagulation by IV nitroglycerin at clinically relevant doses.