Aspirin 4 Acetylsalicylic Acid Has Been the Mainstay of the Home Medicine Cabinet for Generations, but Its Mode of Action Is Not Yet Fully Understood
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s FEBRUARY 111113 February 1993 Aspirin 4 Acetylsalicylic acid has been the mainstay of the home medicine cabinet for generations, but its mode of action is not yet fully understood. Ink 8 You’re looking at it now without seeing it. The printing on this page is really a complex mixture of chemicals. Car Cooler 11 When your car has been parked in the sun and it’s hotter than an oven, the “pssst” of this spray can bring relief. MysteryMatters 12 Saint’s Blood 12 The solid, dried blood has liquefied many times during the last 500 years. Is it a miracle or the work of a clever medieval chemist? The Puzzle Page 16 Chemistry Rhyme Time ASPIRIN By Gail Marsella Scene Three. The year is 1992. A and are some of the oldest and most high school student, diligently study frequently used drugs. Willow trees Scene One. The year is 1614; the ing for an exam, develops a contain salicin, oil of wintergreen is place is eastern Massachusetts. Four headache after several hours of methyl salicylate, and aspirin is members of the Wampanoag tribe of intense concentration. She goes to acetylsalicylic acid (see Figure 1). American Indians have developed the medicine cabinet, takes out a bot high fevers. The shaman ventures out tle marked "aspirin ," and swallows Painful discoveries into the forest, where he carefully col two pills with a glass of water. In less At some time in the remote past, a lects some leaves, roots, and bark than an hour, her headache is gone. primitive physician may have tried from a willow tree. He returns home, Taking medicine to relieve pain, using the bark from a willow tree to grinds up the plant material, and fever, and inflammation is a ritual that relieve a patient's pain or fever. brews it in water. The patients drink has been repeated through most of Unlike so many other plant remedies the hot herbal tea, and bathe in a recorded history. Willow tree bark that were tried, this one worked! cooled solution of the ground bark. extract, oil of wintergreen, and aspirin Many cultures have a history of Within hours, the fevers are lower, are similar in molecular structure and herbal medicine, so the same discov and the sick people are resting com metabolic effect. All three belong to a ery was probably made hundreds of fortably. group of chemicals called sa/icy/ates, times, beginning with very early Scene Two. The year is 1846; the humans. place is London, England. On the day These first investigations were of the Prince's annual ball, the Grand mostly "trial and error" (much to the Duchess is suffering from severe joint dismay of the suffering patient). pain due to arthritis. She sends for Studying the actual chemistry of med her doctor, and is given oil of winter icinal plants began only in the 1800s. green to swallow. In a short time the Imagine the difficulties the early inflammation in her joints lessens, chemists faced! Identifying the active and she can move without pain. The ingredient in a mound of willow tree duchess attends the ball, and fulfills bark was a formidable task. From the her social obligations. hundreds of chemicals contained in , 11-- _ ./-1 °II C ~.t n '-OCH3 '( by Dr. Hoffman nearly a century ago. \J-OH Win~~~;:een l~ When acetylsalicylic acid ages, it may decompose and return to salicylic Methyl Salicylate ..--... S.\!1 acid and acetic acid. If you have a '\.--- _ 'V If' very old bottle of aspirin around the /HYd'OIYS;S \\y~7?I; house, open it and take a sniff. It may /~/ smell like vinegar, because vinegar is ~/)\----\ ~I/ \~/ dilute acetic acid. ~{I ~\ J ~. \~~~~~~~r0~c) )j/~---- Something for everyone \ \', \\ Researchers have been puzzled by ~1\\ \ ~" \\.~ ..4P! \ the many and varied actions of ~ /' 1 1'\\.' '\ ~/- lJ \ -..... I aspirin. This one drug not only il. \ 1\\ \, Salicylic Acid // ,""- l • ,{ I \' \ IY I l \ I " ", f \\ ° Ii \ V \\ A' . O-C-CH3 splnn g Acetylsalicylic Acid Figure 1. Salicylates have been used as painkillers since ancient times. Salicin can be extracted from the bark of willow trees, and methyl salicylate is found in winter Take a"BAVER~ BREAK"! green plants, also called teaberry. Aspirin was first prepared by the acetylation of salicylic acid, which results from heating a solution of salicylic acid and acetic acid in the presence of sulfuric acid. the bark, it was nearly impossible to In 1899, a German scientist named purify the single chemical capable of Felix Hoffman suggested acetylsali relieving pain and fever, especially cylic acid as a good alternative to sal when the chemist was working with icylic acid. He had been searching for out the computers and analytical a drug that would give his elderly equipment we routinely use today. father relief from severe arthritis, and In the mid-1800s the German he stumbled upon acetylsalicylic acid chemist Hermann Kolbe synthetized after trying phenyl salicylate and sodi salicylic acid (so named because the um salicy1ate without success. The scientific name for willow is Salix) in new drug was named aspirin-a from his laboratory by heating phenol with acetyl, and spirin from spiraea (mead carbon dioxide. Although several dif owsweet flower), one of the natural ferent plants are able to relieve fever plant sources of salicylic acid. Hoff and pain, the active chemical part of man worked at the Bayer Company, all of them is salicylic acid. Unfortu which marketed the new remedy with 1Take 2 Bayer Aspirin for your headache. 2 Sit down and relax. nately, salicylic acid is very irritating great success. Aspirin became a With Bayer Aspirin and afew minutes' rest, you'll feel fine in practically no time. Try it. to the stomach-so much so that mainstay of the home medicine cabi 3 -makeWh" 'h'youho,feel."'h,,tense, "dheadachy,h;gh h,m;d;',all worn g,tout,'"justdo.,stop I a~take I many patients preferred their aches net; today, Americans swallow nearly for a few minute.s a "Bayer Break"! Thanks to :. -! Instant flaking action, Bayer brings the fastest, gentlest 'relief you can set from hot·weather aches and pains,;; •-- and fever to the severe heartburn 50 million tablets a day. N"";m.y",,,'''h,,'bo,t,''',k,'''.''''.''''.'' We promiseyou'Jlfeel betterfastl ill caused by the remedy. So the search Aspirin can be made easily in the was on for a chemical that was simi laboratory by reacting acetic acid with This aspirin advertisement from 1961 lar to salicylic acid-but without the salicylic acid to produce acetylsali looks out of date, but modern ads side-effects. cylic acid, the same procedure used promote the same benefits. CHEM MATTERS, FEBRUARY 1993 5 relieves fever, pain, and inflamma tion, but also inhibits blood clotting. Which of these people should be cautious about taking aspirin for their pain-the boy with sore muscles or the girl with the flu? Some new evidence indicates that it may help prevent some types of heart attacks if taken regularly. None of these effects seems to be very close ly related. Despite its many years of use, aspirin's mode of action is only partly understood. Unlike many painkillers (such as narcotics) that act directly on the ner vous system, aspirin seems to relieve pain primarily by stopping the produc tion of hormone-like chemical mes sengers called prostaglandins. Hormones are messengers that are produced in one part of the body and act on another. Prostaglandins, in contrast, are produced by the same tissue as the one they act upon. They are produced in very tiny amounts and are degraded within a few min utes, but in their short lifetime they exert a powerful influence on the body. Prostaglandins regulate diges tion, kidney output, reproduction, blood circulation, and some nervous system functions. Aspirin interferes with the action of one particular enzyme, cyclooxyge nase, which acts at the beginning of a chain of prostaglandin synthesis. As a result, all the prostaglandins pro duced by this chain of reactions are suppressed. All of aspirin's numerous effects-reducing fever, enlarging blood vessels, reducing clotting of the Reye's syndrome is a rare, potentially fatal illness that can strike people blood-eome from altering the bal who have used aspirin to treat symptoms of a viral infection, such as flu or ance of prostaglandins, even though chicken pox. No age group is immune, but Reye's syndrome most com aspirin itself disturbs only a single monly strikes young people from infants to age 19. Early symptoms include reaction. severe vomiting and drowsiness; later symptoms may include confusion, irrational behavior, delirium, convulsions, and coma. There is no cure for Too much of a good thing Reye's syndrome, but early treatment can improve the chances of recov If a person takes an overdose of ery. The disease affects all organs of the body but especially the liver aspirin, the salicylic acid absorbed by (where it causes accumulation of fat) and the brain (where it increases the stomach and intestine lowers the pressure). Exactly how aspirin interacts with the viral infection is still pH of the blood. The body responds unclear. by breathing more rapidly to get rid of Since 1986, all aspirin labels carry the warning, "Children and teenagers some carbon dioxide, in an attempt to should not use this medicine for chicken pox or flu symptoms before a doc reduce the blood acidity. Then the tor is consulted about Reye's syndrome, a rare but serious illness." Read kidneys start to work overtime to labels carefully; confusion can arise when the product is not called aspirin, excrete the excess acid from the but contains aspirin as one of its ingredients (such as Alka-Seltzer, Anacin, blood, and the person may become Ecotrin).