Acetylsalicylic acid (uh-SEE-till-sal-in-SILL-ik As-id, or uhse-
TEEL-sal-ih-SEEL-ik AS-id), more commonly known as
aspirin, is the world’s most commonly used therapeutic drug.
By one estimate, about 137 million aspirin tablets are taken
every day throughout the world. The drug is also known by
other names including: o-acetoxybenzoic acid; 2-(acetyloxy)-
benzoic acid; 2-carboxyphenyl acetate; and benzoic acid,
2-hydroxyacetate, in addition to about ten other systematic
names and many common names.
The analgesic properties of willow tree bark, from which
salicylic acid comes, have been known for well over 3,500
years. They were first described in Egyptian scrolls dating to
about 1550 BCE and were later recommended by a number of
ancient authorities, including the famous Greek physician
Hippocrates (c. 460–370 BCE), the Roman encyclopedist Aulus
Cornelius Celsus (c. 10 BCE–date of death unknown), the
Roman philosopher Pliny the Elder (23 CE–CE), and the Greek
physician Pedanius Dioscorides (40–90 CE).
In the period from 1828 to 1829, the active ingredient in
willow bark was first isolated by three individuals, the German
pharmacist Johann Bu¨chner (dates not available), the
French chemist Henri Leroux (dates not available), and the
the Italian chemist, Raffaele Piria (1815–1865). Bu¨chner gave
the name salicin to the bitter-tasting yellow crystals
extracted from willow bark after the Latin name for the
willow tree, Salix. In 1853, the French chemist Charles Frederick
Gerhardt (1816–1857) developed a method for reacting
salicylic acid (the active ingredient in salicin) with acetic
acid to make the first primitive form of aspirin.
For many years the way aspirin works in the body was not
understood. Scientists now know that the compound’s helpful
effects come from its action on prostaglandins. Prostaglandins
are hormone-like substances released by cells that are injured.
They cause the body to release other substances that sensitize
nerve endings to pain and start the healing process. Aspirin
blocks prostaglandin production, thus relieving the sensation
of pain and the inflammation that are the body’s response to
injury. Aspirin reduces fever by acting on the region of the
brain that regulates body temperature and heart rate. Prostaglandins
block the body’s natural system for producing heat
so that by blocking the release of prostaglandins, aspirin
allows the regulation of body temperature to continue as
usual. Aspirin’s protection against heart attack and stroke
occur because of its effect on one special type of prostaglandin,
known as thromboxane A2. Thromboxane A2 promotes
the accumulation of cells that takes place when a blood clot
forms. By blocking or slowing down the production of thromboxane
A2, aspirin prevents the formation of blood clots and,
hence, the probability of heart attack and stroke.
The modern method for making aspirin was developed in
1897 by the German chemist Felix Hoffman (1868–1946), an
employee of the German chemical manufacturer Bayer AG
Chemical Works. In this procedure, phenol (C6H5OH) is treated
with sodium hydroxide and carbon dioxide to make salicylic
acid. The salicylic acid is then reacted with acetic acid
(CH3COOH) to make acetylsalicylic acid, or aspirin. The preparation
of aspirin by this procedure is quite simple and is often
assigned to students in beginning high school and college chemistry
classes. Aspirin tablets themselves include only acetylsalicylic
acid, to which is added a small amount of water, starch
and lubricant that act as a binder to hold the tablet together.
The exclusive use of aspirin is as a medicine. It has three
important properties as a drug. It relieves pain, reduces
inflammation, and reduces fever. In addition to its effectiveness
in treating these medical symptoms, it is inexpensive
and available in a variety of forms, including chewable
tablets, extended-release formulations, effervescent tablets,
and even in chewing gums. Aspirin is often prescribed in low,
daily doses as a preventative measure for individuals at risk
for heart attack and stroke.
While aspirin has many medical benefits, it is not without
risk for some individuals. Some people are allergic to the
compound and can not tolerate even a low dose. Such individuals
experience a number of symptoms if they ingest high
doses of aspirin, symptoms that include ringing in the ears,
nausea, vomiting, dizziness, confusion, hallucinations, coma,
seizures, rapid breathing, fever, and, in the most severe
cases, death. Aspirin use is not recommended in children
under the age of twelve who show symptoms of viral infections
because it can lead to an extremely rare but deadly
complication known as Reye’s syndrome.
