The 1¢ Wonder Drug
For: Speaking of Wellness, April 2002
Aspirin is the most popular drug in the world today (50 billion tablets swallowed annually) as well as the cheapest: a penny or less per tablet for generic versions. Advertising to the contrary, it is futile to pay more. It is hard to imagine life without aspirin, though it has been around for only a century. What did people do before that for a headache, high fever, a toothache, a sprain, menstrual cramps, or the miseries of arthritis?
Aspirin is acetylsalicylic acid and is based on salicylic acid, which was originally extracted from willow bark. It is a nonsteroidal anti-inflammatory drug, or NSAID (others include ibuprofen, with brand names such as Advil or Motrin, as well as prescription NSAIDs used for arthritis and other conditions). Aspirin can reduce swelling, relieve pain, and reduce fever. Unlike some other anti-inflammatory agents, such as prednisone, aspirin is not a hormone (hence the term "nonsteroidal"). Unlike some other pain relievers, it is not an opiate and thus is not addictive or habit-forming.
Besides its efficacy as a pain reliever and anti-inflammatory agent, aspirin is now known to keep platelets in the bloodstream from sticking together and blocking blood flow. Thus millions now take it daily or every other day to reduce the risk of the clots in the bloodstream that lead to heart attacks and strokes. When you have symptoms of a heart attack, such as chest pain, standard advice is to chew one aspirin tablet immediately while you seek medical help. Diabetics are now advised to take a daily dose, under medical supervision, since they're at high risk for heart attacks. Indeed, aspirin seems to have an ever-expanding repertory. There's preliminary evidence it may help prevent colorectal cancer and Alzheimer's Disease. There have been investigations of its possible protective action against breast cancer, though so far the evidence is not clear.
How aspirin works
Science has only recently deciphered the mystery of how aspirin works, and the biochemistry is complicated. All cells, except red blood cells, manufacture hormones called eicosanoids. These include the prostaglandins and thromboxanes. Some of these control muscle contractions, others the dilation of blood vessels and blood clotting. Others cause pain when cells are injured or infected and produce inflammation. Aspirin blocks the action of a group of enzymes ("COX") that synthesize the prostaglandins. Thus aspirin blocks the effect of prostaglandins in producing pain and inflammation and in clotting. (It was recently discovered that red blood cells can promote clotting on their own, independently of prostaglandins, but enough aspirin can block that, too.)
Other drugs can relieve pain, and other NSAIDs, such as ibuprofen, can relieve both pain and inflammation, menstrual cramps, and other problems, but aspirin is unique in its blood-thinning ability. Because of its particular structure, aspirin's effect on the platelets in the blood is irreversible. It lasts until the platelets are replaced (a cyclic process—a platelet "lives" about seven days). The catch is that aspirin doesn't discriminate and also inhibits another prostaglandin that protects the stomach lining. It's this that can cause gastrointestinal problems.
Why we need a better aspirin
If aspirin had been invented recently, it might not be an over-the-counter item because of its potential side effects. Taken daily, on a long-term basis, all NSAIDs, including aspirin and ibuprofen, can lead to serious gastrointestinal bleeding, ulcers, and even death in a small percentage of users. Because so many people now take aspirin and other NSAIDS regularly for heart attack prevention or arthritis pain, that "small percentage" could add up to large numbers, but at present no one really knows how many people develop gastrointestinal bleeding from NSAIDS. According to an estimate by Dr. James Fries of the Stanford University School of Medicine, about 76,000 Americans are hospitalized each year with gastrointestinal bleeding from NSAID use, and about 10% of these people die. Dr. Fries's figures were based on high-risk patients, such as those with rheumatoid arthritis taking very high doses over very long periods, and people with other risk factors for gastrointestinal bleeding. Even higher figures are commonly cited, but these have little or no basis.
Aspirin can directly irritate the stomach, but this local effect is not as important as the systemic effect. That's why taking aspirin with meals or using buffered or enteric-coated aspirin does not do much to protect you from damage. Yet the benefits far outweigh the risks, because aspirin is the only NSAID that acts irreversibly to prevent clotting. A new form of aspirin, called COX-2 inhibitors, is available only by prescription, with the brand names Celebrex and Vioxx. These "smart" aspirins relieve pain and inflammation with a much lower incidence of gastrointestinal side effects, but are not a substitute for the low-dose aspirin used to prevent heart attacks. (The Wellness Letter discussed these in June 1999.)
Ibuprofen and other NSAIDS appear less likely to cause gastrointestinal bleeding at high doses than aspirin, but for the equivalent level of pain reduction, the side effects may not be very different. Low-dose aspirin, taken to prevent heart attacks, is unlikely to cause gastrointestinal bleeding. Aspirin and other NSAIDs are also safe when taken only occasionally as pain relievers.
Acetaminophen—better?
Acetaminophen, sold as Tylenol, Panadol, and Anacin-3, among other brand names, is an effective pain reliever and will lower fever. As such, it is a useful drug, but limited. It has no effects against inflammation. It does not thin the blood, nor can it prevent heart attacks. It does not produce gastrointestinal bleeding, but it can cause liver and kidney damage in high doses over the long term, especially when combined with alcohol. How it works to relieve pain is not well understood. It is recommended for children 16 and under for pain relief and fever because aspirin can precipitate a rare disease called Reye's Syndrome in children with chicken pox or flu. It is also usually the first choice for osteoarthritis (which isn't primarily an inflammatory disease.)
Aspirin and NSAID guidelines
• If you take aspirin, ibuprofen, or another NSAID occasionally for pain relief, or low doses for heart attack prevention, you are probably safe from gastrointestinal side effects. What may pose a danger in some people is chronic daily use. If you are using any NSAID daily, you need medical supervision.• The standard dose of aspirin for heart attack prevention is a baby aspirin (81 milligrams) daily or half a regular aspirin (162 milligrams) every other day. But baby aspirin is unnecessarily costly. We suggest buying a generic aspirin and an inexpensive pill-cutter to halve or quarter the tablets. Important new research has shown, however, that those taking low-dose aspirin need a booster dose to make sure that clots don't form. One whole aspirin should thus be substituted for the low dose on the first and fifteenth of every month.
• If you have some condition that might be helped by regular NSAID doses (heart disease, arthritis, chronic pain of any kind), ask your physician these questions: What is the lowest dose I can take? Would I be better off with ibuprofen or another NSAID instead of aspirin? Would I be better off with acetaminophen? Am I at high risk for stomach bleeding? What are the warning symptoms?
• Aspirin can interact with other drugs, and one NSAID can interact with another. Be sure your doctor knows about other drugs you take, even over-the-counter ones.
UC Berkeley Wellness Letter, May 1998
