The hemodynamic effects of intravenously administered trinitroglycerin (TNT) and isosorbide dinitrate (ISDN) in stechiometric equivalent doses were studied in 30 patients with acute myocardial infarction. Both drugs were given over 30 min in every patient, and the stability of the condition of the patient was checked by administering the initial drug again. Measurements were made by right heart catheterization using a balloon tip thermodilution catheter and a catheter in the radial artery. TNT and ISDN have different hemodynamic effects. By multivariate analysis it could be shown that TNT is a venous dilator, lowering mainly pulmonary capillary pressure, while ISDN acts more as a mixed vasodilator, diminishing mainly peripheral vascular resistance and increasing cardiac output. These drugs have, therefore, a different spectrum of indications in patients with acute myocardial infarction.

Clinical efficacy of 5 mg per 24 hours transdermal nitroglycerin was studied in a placebo controlled, randomized, double-blind crossover trial, with three days wash-out period at the beginning, in 40 patients with chronic stable angina pectoris during two periods of 14 days. Assessment was carried out by means of a diary method, by the multistage treadmill exercise test, five hours after dosing, and by 24-hour ambulatory ECG recordings. Nitroglycerin patch demonstrated significant improvement of exercise tolerance comparing to placebo, in exercise time to the onset of angina pectoris and ST-segment depression of greater than or equal to 1.0 mm (+45% and +47%), in maximum walking time (+13%), as well as in diminished severity of maximum angina (-38%), in lower maximal ST-segment depression (-32%) and in faster recovery of ST-depression 3 and 6 minutes after the test (-28% and -44%). Nitroglycerin patch showed 33% less angina attacks, mainly severe and moderate, resulting in 37% less sublingual nitroglycerin consumption. A significant fall in the number of ST-segment depression episodes of 1.5 mm or more (-60%) was shown in the 24-hour ECG. All these changes were confirmed to be significant compared to placebo values, at a level of P less than 0.01, by multivariate analysis. This study revealed a positive effect of low dose nitroglycerin patch on improvement of exercise functional capacity and signs of myocardial ischaemia after 14 days of continuous therapy.

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