What Is Aspirin? What Is Aspirin For?

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Main Category: Pain / Anesthetics
Also Included In: Arthritis / Rheumatology;  Headache / Migraine
Article Date: 20 Aug 2009 - 0:00 PDT

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Aspirin, or acetylsalicylic acid (ASA) is a salicylate drug, and is generally used as an analgesic (something that relieves pain without producing anesthesia or loss of consciousness) for minor aches and pains, to reduce fever (an antipyretic), and also as an anti-inflammatory drug.

Aspirin has also become increasingly popular as an antiplatelet - used to prevent blood clot formation - in long-term low doses to prevent heart attacks and strokes in high risk patients. Nowadays, aspirin is often given to patients immediately after a heart attack to prevent recurrence or cardiac tissue death.

Aspirin is a non-steroidal anti-inflammatory drug (NSAID). NSAIDs are medications with analgesic, antipyretic (something that reduces a fever), and in higher doses anti-inflammatory effects. Non-steroidal means they are not steroids, which often have similar effects. As analgesics, NSAIDs are generally non-narcotic (do not cause insensibility or stupor). The most prominent NSAIDs are aspirin, ibuprofen and naproxen - mainly because most of them are OTC (over-the-counter, no prescription required) medications. Aspirin was the first discovered NSAID.

Aspirin in its present form has been around for over 100 years and is still one of the most widely used medications in the world. It is estimated that approximately 40,000 metric tons of it is consumed annually. Aspirin is a trademark owned by German pharmaceutical company Bayer; the generic term is acetylsalicylic acid (ASA).

A short history of aspirin

Acetylsalicylic acid (aspirin) is a derivative of salicylate, which can be found in such plants as willow trees and myrtle.

• ca. 3000 BC - An ancient Sumer stone tablet from the Third Dynasty of Ur of medical text mentions willow-tree based remedies. However, it does not specify what the remedies were for. Sumer was a civilization and a historical region located in Mesopotamia, southern Iraq, known as the "Cradle of civilization".


• ca. 1543 BC - The Ebers Papyrus, an ancient Egyptian medical text, mentions willow and myrtle being used for remedies to treat pain, fever and inflammation. Some say that although the text is ancient it may be a copy of the original.


• ca. 460-370 BC - Hippocrates, a Greek physician, recommended willow bark preparations for childbirth pains and controlling fever.


• ca. 30 AD - Aulus Cornelius Celsus, an encyclopedist, mentioned willow leaf extract for "redness, heat, swelling and pain" - what he termed as "the four signs of inflammation" in his De Medicina, believed to be the only surviving section of a much larger encyclopedia.


• ca. 40-90 AD - Pedanius Dioscorides, a Greek physician, pharmacologist and botanist, mentioned remedies from the willow plant in his De Materia Medica (Regarding Medical Matters), a five-volume book that was translated into Latin (he wrote the original in Greek).


• 23-79 AD - Gaius Plinius Secundus (known as Piny the Elder), a naturalist, author and naval commander in the early Roman Empire, mentioned willow plant remedies in an encyclopedic work called Naturalis Historia (Natural History).


• 200 AD - remedies derived from the willow plant were widely used throughout the Roman Empire and Arab civilizations.


• Before 1492 - Before the Europeans ever set foot in America, the Huron, Mohawk, Cree, Chippewa and many other north American tribes had been using the bark and twigs of the American White Willow to make remedies and teas for the treatment of pain relief, inflammation and fevers. Ancient Aztec and Mayan folklore in Mexico and Central America mention the use of 'sauce' (willow) for similar treatments.


• 1763 - Edward Stone, England, a Church of England rector wrote a letter to the Royal Society which described some of his experiments with willow bark extract to cure ague - a word used to describe intermittent fever, pain, chills fatigue; probably malaria. He compared the effects of willow bark to Peruvian bark, which contains quinine (and attacks the infectious cause of malaria). He noticed that the willow bark relieved symptoms of ague, while the Peruvian bark was more effective. He had discovered salicylic acid, the active ingredient in aspirin. Willow bark derived remedies subsequently became much more popular in England than the more expensive Peruvian bark.


• 1800s - Organic chemistry began to develop rapidly in Europe. Several scientists tried to isolate and purify the active ingredients of many medications, including willow bark.


• 1828 - Joseph Buchner, a German chemist, managed to obtain what were then considered as fairly pure salicin crystals.


• 1829 - Henri Leroux, a French chemist obtained purer forms.


• 1830 - Johann Pagenstecher, a Swiss pharmacist, said he had discovered a new painkiller which he had isolated from the common remedy of meadowsweet Spiraea ulmaria, which we know today contained salicylic acid, flavone-glycosides, essential oils and tannins.


• 1838 - Raffaele Piria, an Italian chemist, managed to devise a way of obtaining a more powerful acid form of willow extract, which he called salicylic acid. Karl Jacob Lowig, who was trying to isolate the active ingredients in Spiraea, eventually found out that it was the same salicylic acid that Piria had identified.


• 1840-1894 - During this period various forms of salicylate medicines, including salicin, salicylic acid, and sodium salicylate became more widely used by doctors for the treatment of pain, fever and inflammation. However, their gastric irritation side effects were considerable.


• 1980 - Friedrich Carl Duisberg, a German chemist and industrialist became head of the management of Bayer, a large German company. He created a pharmaceutical division within the company and placed Arthur Eichengrun, a former university chemist in charge. Heinrich Dreser was placed in charge of a pharmacology group for testing new drugs.


• 1894 - Felix Hoffman, a German chemist, joined Bayer's pharmaceutical group. These three men, Dreser, Eichengrun and Hoffman, were to become key players in the development of acetylsalicylic acid as Aspirin.


• 1897 - Hoffman's boss, Eichengrun, assigned him to find a substitute for salicylic acid; one that did not irritate the stomach so much. Hoffman eventually found the best way of making acetylsalicylic acid (ASA), from salicylic acid refluxed with acetic anhydride (reflux = to boil a liquid in a vessel attached to a condenser so that the vapors continuously condense for reboiling). The ASA was sent to the pharmacology group for testing, and initial results were good. However, the ASA did not proceed to clinical trials because Dreser was concerned about salicylic acid's effect on weakening the heart - probably because of the doses given to patients with rheumatism. Hoffman had progressed in developing diacetylmorphine, which became Dreser's focus for development - this eventually led to the invention and branding of heroin.
  
  Eichengrun, annoyed with Dreser's reluctance, wanted to pursue clinical trials with ASA, so he approached Felix Golgmann, Bayer's Berlin representative, and arranged for surreptitious clinical trials. The trials gave good results, without the hitherto complications that occurred with salicylic acid. Dreser still objected, but big boss Duisberg ordered full testing.
  
  Eventually, Dreser accepted that ASA had great potential and Bayer proceeded with production.
  
  Dreser wrote a report about the findings, but did not mention Hoffman or Eichengrun in it. For many years Dreser said Hoffman was the sole discoverer of Aspirin.
  
  Arthur Eichengrun died in December 1949. Earlier in that year he wrote an article Fifty Years of Aspirin in which he said that Hoffman did not know the purpose of his research and that Hoffmann's role was restricted to the initial lab synthesis using Eichengrun's process and nothing more.
  
  Controversy continued for many decades, and still does so to a certain extent today, as to who was primarily responsible for aspirin's development. According to Bayer today, it was Hoffman. Some historians agree while others don't. Eichengrun went on to hold 47 patents for various inventions. However, he never disputed aspirin's claim to priority until half a century later, even though he had ample opportunity to do so.


• 1915 - Aspirin became available as an OTC (over-the-counter, no prescription required) medication in tablet form.


• 1920s - Aspirin became a commonly used medication for the treatment of neuralgia, lumbago and rheumatism.


• 1948 - A Californian GP (general practitioner, primary care physician) reported that many of his patients who regularly took aspirin had significantly lower rates of heart attacks.


• 1952 - Chewable Aspirin became available.


• 1969 - Apollo Moon astronauts had Aspirin included in their self-medication kits.


• 1988 - The FDA (Food and Drug Administration), USA, proposed use of aspirin for reducing risk of recurrent myocardial infarction, heart attack, and preventing first myocardial infarction in patients with unstable angina. The same agency also approved aspirin use for the prevention of recurrent mini-strokes (recurrent transient-ischemic attacks) in men, it also made aspirin standard therapy for men after suffering a stroke.


• 1988 - A study by Dr. Charles Hennekens and team found that aspirin dramatically reduces risk of a first myocardial infection. Hennekens later found the same for cardiovascular disease.


• 1998 - A major study, The Hypertension Optimal Study, published in The Lancet showed that low dose ASA combined with medication for hypertension significantly reduced the risk of myocardial infarction and major cardiovascular events in patients with hypertension.

What are the therapeutic uses of aspirin?

Aspirin is one of the most commonly used drugs for the treatment of mild to moderate pain, as well as migraines and fever. For the treatment of moderate to severe pain it is frequently used along with other opioid analgesic and other non-steroidal-anti-inflammatory drugs.

Below is a list of most therapeutic uses of aspirin:

• Mild to moderate pain


• Moderate to severe pain combined with other medications


• Rheumatic fever (in higher doses)


• Rheumatic arthritis (in higher doses)


• Many other inflammatory joint conditions (in higher doses)


• To inhibit platelet aggregations (blood clot formations) to reduce risk of transient ischemic attacks and unstable angina (in lower doses)


• For the prevention of stroke (in lower doses)


• For the prevention of myocardial infarction in patients with cardiovascular disease. According to researchers from the University of California, San Diego, USA, chewable aspirin is better than other forms.


• In the treatment of pericarditis


• In the treatment of coronary artery disease


• In the treatment of myocardial infarction


• Colorectal cancer - men and women who were diagnosed with colorectal cancer and began regular use of aspirin had a lower risk of overall and colorectal cancer death compared to patients not using aspirin, according to researchers at Massachusetts General Hospital and Harvard Medical School, Boston, USA.


• Cancer prevention - taking aspirin in your 40s could cut the risk of cancer developing later in life, according to researchers from the Cancer Research UK Centre for Epidemiology at Queen Mary, University of London, UK.

Aspirin and children

Acetaminophen (paracetamol, Tylenol) and ibuprofen are generally used for children; not aspirin. Aspirin and salicylate NSAID usage in children raises the risk of developing Reye's Syndrome. In some countries, such as the UK, aspirin is only occasionally used in children under specialist supervision for Kawasaki disease and to prevent blood clot formation after heart surgery.

Low dose aspirin

Low-dose aspirin (75mg per day) is used as an antiplatelet medication - to prevent the formation of clots in the blood.

Low-dose aspirin may be given to patients who had:

• A coronary artery bypass graft operation
• A heart attack
• A stroke
• Atrial fibrillation
• Acute coronary syndrome

The following people may also be given low-dose aspirin if the doctor believes they are at risk of heart attack or stroke:

• Patients with high blood cholesterol levels
• Patients with hypertension (high blood pressure)
• Patients with diabetes
• Some smokers

The following patients may also be advised to take low-dose aspirin:

• Those with damage to the retina (retinopathy)
• Those with kidney damage (nephropathy)
• Some patients who have had diabetes for over ten years
• Some patients who are taking antihypertensive medications

In all these cases, low-dose aspirin will be taken daily for the rest of the patient's life.

Precautions

Aspirin is not recommended for the following patients:

• People who have a peptic ulcer
• Patients with hemophilia or any other bleeding disorder
• People with a known allergy to aspirin
• People who are allergic to any NSAIDs, such as ibuprofen
• Children under 16 years of age (unless under specialist medical supervision)

The following people should be cautious about taking aspirin, and should only do so if the doctor agrees:

• Patients with asthma
• Patients with uncontrolled hypertension
• People who have had a peptic ulcer (even though they don't now)
• Patients with liver problems
• Patients with kidney problems

If you are planning to have a surgical operation you should tell your doctor if you are taking regular aspirin. In many cases patients will be asked to stop taking the aspirin for seven days before the operation.

Pregnant or breastfeeding patients may take low-dose aspirin, but only under their doctor's supervision. High-dose aspirin is not recommended.

Drug interactions

Sometimes one medication can undermine the efficacy of another medication - this is called drug interaction. Below is a list of the most common drugs that aspirin interacts with (there are more):

• Anti-inflammatory painkillers - such as diclofenac, ibuprofen, indometacin, and naproxen increase the risk of stomach bleeding if taken in combination with aspirin.


• Methotrexate - used in the treatment of cancer and some auto-immune diseases. Aspirin can make it harder for the body to eliminate methotrexate, resulting in high and potentially dangerous levels of methotrexate in the body.


• SSRI (selective serotonin reuptake inhibitors) antidepressants - drugs, such as citalopram, fluoxetine, paroxetine, venlafaxine and sertraline, taken with aspirin can increase the risk of bleeding.


• Warfarin - this is an anticoagulant drug (a blood thinner); it stops the blood from clotting. Aspirin taken with warfarin can reduce the drug's anticoagulant effects, increasing the risk of bleeding. In some situations, however, a doctor may prescribe aspirin together with warfarin.

What are the side effects of aspirin?

The most common side effects of aspirin are:

• Irritation of the stomach or gut
• Indigestion
• Nausea

The following side effects are possible, but less common:

• Asthma symptoms may worsen
• Vomiting
• Inflammation of the stomach
• Stomach bleeding
• Bruising

An extremely rare side-effect of low-dose aspirin is hemorrhagic stroke.

Written by Christian Nordqvist


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