Which one of the following statements is a characteristic of both nitroglycerin and amyl nitrite?

Which one of the following statements is a characteristic of both nitroglycerin and amyl nitrite?

1.They may be effectively used in the prophylaxis of angina pectoris
2.They are useful for treating cyanide poisoning
3.They may cause methemobglobinemia during chronic industrial exposure
4.They may cause orthostatic hypotension

sol:

Both organic nitrates and nitrites relax smooth muscle and produce venodilation, resulting in orthostatic hypotension. Therefore, patients should sit down before administering sublingual nitroglycerin or inhaling amyl nitrite. Only nitrites such as amyl nitrite can cause methemoglobinemia and are therefore used to treat cyanide poisoning; methemoglobin has increased affinity for cyanide compared with normal hemoglobin. Because amyl nitrite is a volatile liquid that must be administered by inhalation, it has no value in the prophylaxis of angina.