Non-Steroidal Anti-Inflammatory Drugs
Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most commonly prescribed categories of drugs worldwide in the treatment of pain and inflammation in many conditions.
NSAIDs are used primarily to treat inflammation, mild to moderate pain, and fever. Specific uses include the treatment of headaches, arthritis, sports injuries, and menstrual cramps. Aspirin is used to inhibit the clotting of blood and prevent strokes and heart attacks in individuals at high risk. NSAIDs also are included in many cold and allergy preparations. Two drugs in this category, ibuprofen and naproxen, also reduce fever.
Uses
NSAIDs are usually indicated for the treatment of acute or chronic conditions where pain and inflammation are present. These drugs also are effective in some neuropathic pain syndromes when used with other analgesics. NSAIDs are generally indicated for the symptomatic relief of the following conditions:
- Rheumatoid arthritis
- Osteoarthritis
- Acute gout
- Inflammatory arthropathies (e.g. ankylosing spondylitis, psoriatic arthritis, Reiter's syndrome)
- Dysmenorrhoea (painful menstruation)
- Headache and migraine
- Postoperative pain
- Mild-to-moderate pain due to inflammation and tissue injury
- Back pain and sciatica
- Sprains, strains, and rheumatism
- Dental pain
- Pain from kidney stones (renal colic)
- To reduce fever
- Other painful conditions, especially where there is inflammation
Drugs in the class
There are several different types of NSAIDs:
- Salicylates: aspirin (Ascriptin, Bayer, Ecotrin), diflunisal (Dolobid, Diflunisal Tablets), salsalate (Argesic SA, Disalcid, Salflex, Salsitab, Mono Gesic)
- Arylalkanoic acids: diclofenac (Voltaren, Cataflam), indomethacin (Indocin)
- 2-Arylpropionic acids (profens): ibuprofen (Motrin, Advil), ketoprofen (Orudis, Oruvail), naproxen (Naprosyn, Alleve), carprofen
- Pyrroles: ketorolac (Toradol)
- Enolic acids (oxicams): piroxicam (Feldene), meloxicam (Mobic)
- Sulphonanilides: nimesulide
- Napthylalkanones: nabumetone (Relafen)
Mechanism of action
NSAIDs work by suppressing the production of fatty acids called prostaglandins that cause inflammation and pain. They do this by blocking the action of an enzyme, cyclooxygenase (COX). This enzyme is responsible for converting precursor acids into prostaglandins.
In the periphery NSAIDs work by decreasing the sensitivity of the nociceptor to painful stimuli induced by heat, trauma, or inflammation. In the central nervous system, they are thought to function as antihyperalgesics and block the increased transmission of repetitive incoming signals to higher centers. In effect, they modulate perception of pain caused by repetitive stimulation from the periphery.
Differences between NSAIDs
NSAIDs vary in their potency, duration of action, and the way in which they are eliminated from the body. Another important difference is their ability to cause ulcers and promote bleeding. The more an NSAID blocks Cox-1, the greater is its tendency to cause ulcers and promote bleeding.
Choice of NSAID for chronic and disabling inflammatory joint diseases like rheumatoid arthritis and osteoarthritis is governed by age, diagnosis, degree of severity, relative gastrointestinal safety, tolerability, and relative efficacy in the given clinical situation. It is a common misconception that all NSAIDs are therapeutically equally efficacious and any one of them could be used for the given indication. Use of multiple NSAIDs should be discouraged. An agent with comparatively less gastrointestinal (GI) side effects like ibuprofen and diclofenac should be preferred in place of indomethacin, piroxicam, or naproxen, which are more gastrotoxic. In conditions where diagnosis is uncertain, the medicine should be empirically chosen and given for a week or so and if the response is adequate it should be continued until side effects mandate its withdrawal. Ankylosing spondylitis responds better to a particular NSAID like indomethacin. It is probably related to its stronger inhibition of prostaglandin synthesis.
Aspirin is a unique NSAID, not only because of its many uses, but because it is the only NSAID that is able to inhibit the clotting of blood for a prolonged period (4 to 7 days). This prolonged effect of aspirin makes it an ideal drug for preventing the blood clots that cause heart attacks and strokes. Most other NSAIDs inhibit the clotting of blood for only a few hours.
The major NSAIDs of potency comparable to opioids are diclofenac and ketorolac. Moderate postoperative pain, for example, may be managed using these agents. The overall analgesic effect of 30 mg of ketorolac is equivalent to that of 6 to 12 mg of morphine. Efficacy has been demonstrated for postsurgical pain including oral, orthopedic, gynecologic, and abdominal procedures. Efficacy for acute musculoskeletal pain has also been shown. Ketorolac causes ulcers more frequently than any other NSAID and is, therefore, not used for more than five days.
Naproxen provides effective relief in acute traumatic injury and for acute pain associated with migraine, tension headache, postoperative pain, postpartum pain, pain consequent to various gynecologic procedures, and the pain of dysmenorrhea.
Possible Side Effects
NSAIDs are associated with a number of side effects. The two main adverse drug reactions, associated with NSAIDs relate to gastrointestinal effects and renal effects of the agents. These effects are dose-dependent, and in many cases severe enough to pose the risk of ulcer perforation, upper gastrointestinal bleeding, and death, limiting the use of NSAID therapy.
- Gastrointestinal adverse reactions. The most common risk of NSAIDs is that they can cause ulcers and other problems in your esophagus, stomach, or small intestine. Common gastrointestinal side effects include: nausea, dyspepsia, vomiting, diarrhea, gastric ulceration/bleeding. Risk of ulceration increases with duration of therapy, and with higher doses. To help protect the stomach, NSAIDs should always be taken with food or directly after a meal.
- High Blood Pressure and Kidney Damage. NSAIDs reduce the blood flow to the kidneys, which makes them work more slowly. When your kidneys are not working well, fluid builds up in your body. The more fluid in your bloodstream, the higher your blood pressure. If you take NSAIDs in high doses, the reduced blood flow can permanently damage your kidneys.
- Allergic Reactions. NSAIDs can also cause extreme allergic reactions. People with asthma are at a higher risk for experiencing serious allergic reaction to NSAIDs. Many specialists recommend that people who have asthma stay away from any NSAID, especially if they have sinus problems or nasal polyps.
Use of aspirin in children and teenagers with chicken pox or influenza has been associated with the development of Reyes's syndrome. Therefore, aspirin and nonaspirin salicylates (e.g. salsalate) should not be used in children and teenagers with suspected or confirmed chicken pox or influenza.
Indomethacin, ketoprofen and piroxicam appear to have the highest prevalence of gastrointestinal adverse drug reactions, while ibuprofen (lower doses) and diclofenac appear to have lower rates.
Serious side effects are especially likely with one nonsteroidal anti-inflammatory drug, phenylbutazone. Patients of age 40 and over are especially at risk of side effects from this drug, and the likelihood of serious side effects increases with age.
Precautions and Contraindications
NSAIDs cannot be used in the following cases:
- Allergy to aspirin or any NSAID
- Aspirin should not be used under the age of 16 years
- During pregnancy
- During breast feeding
- On blood thinning agents (anticoagulants)
- Suffering from a defect of the blood clotting system (coagulation)
- Active peptic ulcer
Conclusions
All NSAIDs are similarly effective. The choice of which NSAID to try first is usually empiric. If one doesn't provide adequate pain control, try switching to another. All NSAIDS when used chronically can be associated with the development of ulcers. Differences in adverse effects seem to exist between different NSAIDs. Follow with your doctor closely and watch for signs or symptoms of gastrointestinal bleeding such as stomach pain and blood in the stools. Some NSAIDs are available in extended-release formulations that require less frequent dosing. |
