Influence of aspirin on the hemodynamic effects of sublingual nitroglycerin

We studied the possible interaction between aspirin and nitroglycerin (NTG) in seven healthy volunteers. Effects of NTG (0.8 mg sublingual spray) were assessed by the decrease in diastolic arterial pressure, increase in heart rate, and decrease in M-mode echocardiographic end-diastolic and end-systolic diameters of the left ventricle. Measurements were performed before and during 30 min after NTG. Plasma levels of NTG were monitored during the experimental procedure. Each of the following trials was repeated three times, in random order, in each volunteer: NTG without aspirin pretreatment, NTG 1 h after 1 g of oral aspirin, and NTG after 8 days of aspirin, 500 mg every 48 h. Aspirin at the 1-g dose level significantly increased the effects of NTG on diastolic blood pressure (p less than 0.05) and left ventricular end-diastolic (p less than 0.001) and end-systolic (p less than 0.001) diameters. Aspirin (1 g) significantly increased (p less than 0.01) mean NTG plasma levels from 0.24 +/- 0.13 ng . ml-1 (control) to 0.37 +/- 0.26 ng . ml-1. We conclude that pretreatment with 1 g of aspirin increases NTG plasma levels and therefore significantly enhances the pharmacodynamic effects of NTG.