Organic nitrates are pharmacological agents used for the treatment of angina. They are are esters of nitrous acid that can take the form of solids, moderately volatile oily liquids (e.g., nitroglycerin) or highly volatile liquids.
Most nitrates undergo rapid hepatic biotransformation and therefore, the route of administration has major impact on bioavailability. The route of administration primarily reflects the desired therapeutic effect.
The effects of nitrates on the heart are to cause direct vasodilation of large epicardial coronary arteries with a resultant redistribution of blood flow to ischemic regions of the endocardium; dilation of arterioles leading to a reduction in afterload; dilation of veins leading to a reduction in preload; and antiplatelet effects. Of the three mechanisms, the reduction in myocardial oxygen demand as a result of decrease in preload and afterload is believed to be of greatest importance in relieving pain in stable angina.