Nitroglycerin Nitroglycerin

Structural Formula Ball-and-Stick Model Space-filling Model h2c-ono2 hc-ono,

h2c-ono2

Year of discovery: 1847 (Ascanio Sobrero at University of Torino); Year of introduction: 1878 (William Murrell at Westminster Hospital); Drug category: Vasodilator; Main uses: Treatment of angina and congestive heart failure; Other brand names: Minitran, Nitro-dur, Nitrolingual, Nitromist, Nitrostat; Related drugs: Isosorbide dinitrate (Bidil, Dilatrate, Isordil), Isosorbide mononitrate (Imdur, Ismo, Monoket).

Nitroglycerin, an organic nitrate also known as glyceryl trinitrate, is a vasodilator used for the treatment of angina (chest pain caused by hypoxia in the heart) and congestive heart failure. It is most commonly applied as a sublingual tablet or transdermal patch.

Nitroglycerin, a highly unstable and explosive substance, was first prepared by the Italian chemist Ascanio Sobrero in 1847. It was later utilized by Alfred Nobel, who became acquainted with Sobrero in Paris, as the key component of dynamite. From this discovery, Nobel made the fortune that was used to establish the Nobel Prize.

In the 1860s, the English surgeon, T. L. Brunton reported that the inhalation of isoamyl nitrite vapor rapidly alleviates angina and reduces blood pressure. However, relief lasted only a few minutes and dosing was uncertain.

Isoamyl nitrite

This observation prompted William Murrell at Westminster Hospital to test the possibility that nitroglycerin might relieve chest pain. He found that nitroglycerin effectively controls angina and that the beneficial effect lasts for about one hour. Nitroglycerin was introduced into clinical practice in 1878 and remains a principal medication for angina. It is interesting that, years later, Nobel was prescribed nitroglycerin as therapy for chest pain.

Nitroglycerin efficiently relieves angina because it dilates the coronary blood vessels and improves oxygenation of the heart. Nitroglycerin is converted in vivo into the molecule nitric oxide (NO) that serves as a trigger of vasodilation.

h2c-0N02 hc-ono2

h2c-0n02

H2C-OH

hc-oh I

H2C-OH

3 n02

Nitric oxide is produced naturally in the body from the amino acid arginine with the enzyme nitric oxide synthase (NOS) as catalyst.

L-Arginine eo

L-Citrulline

L-Arginine eo

L-Citrulline

Nitric oxide has many functions, one of which is regulation of arterial tone and blood pressure. NO is synthesized by the endothelial cells that line blood vessels. It diffuses from the endothelia to the vascular smooth muscle and activates the enzyme guanylate cyclase by binding to the heme iron in the enzyme. (Heme is the structural unit of hemoglobin that carries oxygen in blood.) This enzyme promotes the formation of cyclic guanosine monophosphate (cGMP). The elevation of cGMP levels decreases intracellular calcium and causes relaxation and vasodilation. For their role in the discovery of nitric oxide as a key regulator in the cardiovascular system, Robert Furchgott, Louis Ignarro and Ferid Murad were awarded the Nobel Prize in Medicine in 1998.

NO plays a role in penile erection, in controlling blood clotting by inhibition of platelet aggregation, and in the immune response, wherein it is produced by macrophages. NO is a very reactive, shortlived species which is deactivated with a halflife of less than a minute.1

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