Review Question - QID 100538

Nitrates are commonly prescribed for the management of stable angina. For rapid relief of acute angina, nitroglycerin is given sublingually.

Nitroglycerin is commonly administered sublingually to treat acute angina attacks. Sublingual nitroglycerin rapidly diffuses across oral mucous membranes and into systemic circulation. Both nitroglycerin and isosorbide dinitrate undergo 1st pass metabolism by the liver and therefore take longer to have therapeutic effect when given orally. In contrast, isosorbide mononitrate is 100% bioavailable when given orally. By increasing the amount of nitric oxide (NO) in vascular smooth muscle, nitrates preferentially venodilate, decreasing preload, while also vasodilating the coronary arteries and peripheral arterioles, reducing afterload.

Sanger et al. discuss the management of chronic stable angina. They emphasize that sublingual nitroglycerin is the preferred route of administration for immediate relief of symptoms.

Hall reviews common medical therapies employed in the management of chronic stable angina apart from coronary bypass surgery. Aspirin, nitrates, beta blockers, and calcium channel blockers are all used to decrease cardiac ischemia or prevent infarction.

Incorrect answers:
Answer 1: Oral nitroglycerin is absorbed in the gut and undergoes 1st pass metabolism before being converted to its active form, a process that is too lengthy to combat acute angina.
Answer 3: Intramuscular injections allow for more rapid absorption than subcutaneous route, as the muscle belly has a more profound blood supply, but are still slower than sublingual.
Answer 4: Nitroglycerin is sometimes given IV to patients whose angina is not controlled by sublingual nitroglycerin or beta-blockers. It is not the first line treatment of acute angina, however.
Answer 5: Subcutaneous nitroglycerin injections are absorbed slower than sublingual nitroglycerin applications and are not used to manage acute angina.