Nitroglycerin, << `ny` truh GLIHS uhr ihn, >> also called nitroglycerol, is a powerful explosive. It is the principal explosive ingredient in dynamite. Nitroglycerin also is used by doctors as a heart medication.
As an explosive.
Nitroglycerin is a heavy, clear or straw-colored liquid with a sweet, burning taste. The liquid freezes at slightly below room temperature to form needlelike crystals that explode when heated or broken. An explosion of nitroglycerin is many times more powerful than that of an equal amount of gunpowder.
Chemists once made nitroglycerin by slowly adding glycerol, also known as glycerin, to concentrated nitric and sulfuric acids. After the mixture was stirred, the nitroglycerin formed a layer on top of the two acids. This layer was drawn off and washed, first with water, and then with a solution of sodium carbonate. Today, chemists make nitroglycerin more safely using a continuous process in a smaller device called a Biazzi nitrator.
Ascanio Sobrero, an Italian chemist, discovered nitroglycerin in 1846. For years, nitroglycerin was not used widely because it did not detonate (explode) reliably when ignited. Alfred Nobel, a Swedish chemist, developed a detonating cap that proved ideal for exploding nitroglycerin. In 1867, Nobel patented dynamite, an invention that provided a safe and convenient means for transporting and using nitroglycerin. Nitroglycerin quickly became the most widely used explosive and remained so until about the 1950’s.
As a medication.
Sobrero noted that tasting a tiny drop of nitroglycerin gave him a violent headache. Doctors knew that amyl nitrite, a substance discovered a few years before nitroglycerin, relieved chest pain and lowered blood pressure. The fact that amyl nitrite also caused severe headaches led doctors to study the effect of nitroglycerin on the heart and on blood circulation.
Today, nitroglycerin is used to treat angina, severe chest pain that occurs when the heart does not receive enough oxygen through the blood. Nitroglycerin works by causing the blood vessels to widen, reducing the heart’s workload and permitting more blood and oxygen to reach the heart.
To relieve an angina attack, most patients take nitroglycerin in the form of a tablet that is placed under the tongue or against the cheek, where it slowly dissolves. An oral spray is also used to treat attacks. Swallowing the medication delays its effectiveness because the liver rapidly converts nitroglycerin to slower-acting forms. To prevent angina, a nitroglycerin patch containing a supply of the medication is attached to the skin like an adhesive bandage. The patch slowly and continuously releases nitroglycerin, which seeps through the skin to the bloodstream. Nitroglycerin also may be taken in capsule form or applied as an ointment.
