isosorbide dinitrate /-sôr″bīd/ , an antianginal agent. Its prototype is nitrogycerin. ▪ INDICATIONS: It is prescribed as a coronary vasodilator in the treatment of angina pectoris and congestive heart failure and esophageal spasm caused by GI reflux. ▪ CONTRAINDICATIONS: Closed-angle glaucoma, known hypersensitivity to this drug, concurrent use of drugs for erectile dysfunction, narrow-angle glaucoma, head trauma, or severe anemia prohibits its use. ▪ ADVERSE EFFECTS: The most serious effect is occasional marked hypotension. Flushing, headache, light-headedness, and dizziness may also occur.