Non-prescription analgesics: choosing a product in a confusing market - includes related information

Nutrition Health Review, Summer, 1994 by Margo Perkins

Researchers are only beginning to understand how pain works. Pain is a sign that something is amiss within the body. Substance, P, bradykinins, and prostaglandins are some of the chemicals known to be released by damaged tissue. These substances send the message from a wound or site of injury along nerves to the brain, which then determines the location and intensity of damage. The result may be throbbing migraine, menstrual cramps, or arthritic discomfort.

Non-prescription analgesics can alter the perception of discomfort. Prostaglandins (PGs) are perhaps the most studied of the pain chemicals mentioned above. PGs are known to induce pain, fever, inflammation, and smooth muscle contraction. Drugs like aspirin and acetaminophen work by deactivating an important key enzyme in P.G. production. This is why aspirin and similar drugs are considered "anti-inflammatory." Their use for treatment of minor to intermediate-intensity pain hinges on their ability to halt P.G.s from spreading the alarm.

Aspirin and the Salicylates

Ancient civilizations knew about the power of willow bark in pain and fever relief. The responsible ingredient -- salicylic acid -- endures today in the form of aspirin (acetylsalicylic acid). Aspirin is found in dozens of products, singly or in combinations, as tablets, capsules, powders, chewing gum and in suppositories. Aspirin and its cousins affect P.G.s both at the site of tissue damage and within the nervous system. This is why salicylates are often effective in relieving the joint swelling of arthritis.

Side-effects, however, preclude the use of aspirin. Salicylates directly irritate the stomach lining. Physicians and pharmacists therefore advise taking aspirin with or directly after meals, with a full glass of water to avoid stomach upset or gastrointestinal bleeding. Buffered aspirin sometimes falls short of its claim to prevent gastric irritation. Enteric-coated tablets seem to offer better protection, passing through the stomach intact and dissolving later. People with peptic ulcer, hiatal hernia, and related stomach problems should avoid aspirin and salicylates. Patients who plan to test for occult blood in the stool should discontinue the use of aspirin for three days prior to testing (to avoid a false-positive reading).

Other specific cases for aspirin avoidance include asthma (because of the frequency of allergic reactions) and clotting disorders. Aspirin's interference with blood clotting extends to surgical procedures as well: aspirin should be discontinued for one week prior to surgery or dental extractions.

Gout sufferers risk acute attacks because salicylates interfere with uric acid excretion (a by-product of human metabolism) that crystallizes in joints of the feet, causing intense discomfort. Pregnant patients are warned to avoid aspirin use, particularly in the third trimester. Prolonged labor and increased risk of fetal bleeding can ensue.

Despite these side-effects, some studies indicate that aspirin can have beneficial effects on cardiovascular disease in doses below the standard for pain relief. Researchers are also involved in determining whether aspirin can prevent colon cancer and cataract formation.

The Acetaminophen Track Record

Acetaminophen's motto would seem to be "pain relief without stomach upset," Dubbed APAP for short, acetaminophen became popular in the late 1940s and attained non-prescription status in 1955. APAP works best against P.G.s in the nervous system but poorly at the site of trauma. Acetaminophen is considered a good pain reliever and fever reducer but a poor anti-inflammatory drug, by many. Arthritic patients do not always get adequate pain relief from aspirin substitutes containing APAP.

Lack of stomach irritation and bleeding effects make APAP a better analgesic for ulcer patients and those with clotting disorders. Asthmatics and gout sufferers have less worry about their conditions being worsened by APAP. Acetaminophen is also a better choice than aspirin in children under 12 years of age because of aspirin's alleged association with a rare but life-threatening condition called Reye's syndrome, observed in children with viral illnesses who are given aspirin.

APAP is available as tablets, capsules, pourable granules, in drops, elixirs, and as suppositories. When dosing children, keep in mind that the drops and elixir are not equivalent dose-wise. Read labels carefully.

Both aspirin and acetaminophen are meant for short-duration usage, no longer than 10 days in adults or five days in children for pain relief or no longer than three days for fever relief. Pain or fever which does not go away signifies the need for physician intervention. Long-term, high doses of APAP have been known to result in toxicity to the liver and kidneys. Persons with long-standing alcoholism and liver or kidney disease are already at a higher risk for this type of toxicity and should avoid using non-prescription analgesics without physician consent. Many prescription drugs contain APAP: users of non-prescription aspirin substitutes should check with their physician or pharmacist to avoid excessive doses through "hidden" acetaminophen.